Air Conditioning & Heat Pump Compressor / Condenser Fan or Fan Motor Repair FAQs

Q&A to Diagnose & Fix outdoor unit that won't start, stop, or run

Condenser Fan Wiring FAQs

Reader question: Pioneer heat pump fan reversed direction

hello, new to here, new to heating and cooling. Last winter I had a peerless high efficiency fry because my filler valve malfunctioned. I ended up replacing with a Navian high efficiency boiler. Was... interesting to learn. Since then, I bought a mini split pioneer seer 19? I think it is a 13k btu unit. I installed it following the install instructions to the letter.

I got everything hooked up and my buddy lent me his evacuator. I dried the lines and did the pressure testing and all held perfectly. I then opened the service valve port to charge the line set with freon (whatever the new stuff is called). I could hear the lines charging and again, no leaks.

The gauges were around 270 (according to my buddy as he read the numbers to me) or so while trying to cool. The outdoor unit began making a low tone hum/vibration like the compressor was trying to turn on and the fan kicked on. Nothing. No cooling, no heating.

The line sets didn't even get cold or hot by even a degree difference. The reversing valve must be working (im guessing) because when i call for heat, the fan will come to a stop, pause and then reverse direction. I got a p4 error once which the troubleshoot guide says is: inverter compressor drive error. I have not got that error since. Any idea what this could be? Is it just as simple as the compressor drive error? Is the drive separate from the compressor? On 2020-09-09 by Bobrosss

Mod reply:

Bob,

Thank you for the helpful diagnostic question about your Pioneer brand Mini Split AC unit. The fact that your fan is reversing direction tells me that this is a heat pump and the controls are miswired or oscillating between heating and cooling, or there's a fan wiring error - as the unit's new.

More subtle would be a mis-adjusted or debris-clogged expansion valve or reversing valve.

Note that Pioneer's mini split units come pre-charged with R410A in a volume sufficient to ccommodate refrigerant line lengths up to 25 ft. per circuit. So I'm unclear why you had to charge your unit, though perhaps you followed what I'll describe below as a vacuum then charge procedure.

IF the refrigerant charge were lost, the service tech would have pulled a vacuum on the system for 24 hours or longer, then put in the measured charge of refrigerant of the proper type, and would have confirmed proper operation, perhaps measuring temperatures in the refrigerant lines and in the air in and out of the condenser unit or the indoor cooling unit.

Below is an example - for other readers, of a Pioneer mini-split AC system.

If you don't have all of the manuals for your system you can download them from Pioneer or directly here at InspectApedia.com at

PIONEER HVAC MANUALS Air Conditioners, Heat Pumps, Split Systems, Inverters

I'd contact Pioneer directly at their tech support department to ask for further help with that P4 error.

Contact Pioneer at (800) 919-0150 Web: pioneerminisplit.com/

Reader follow up:

yes, I am not familiar with the proper terms. I did the vacuum and charge thing, meaning I hooked an evacuator pump on the system and then just opened the service valve so the R410a could fill the line set. Thank you for your response. I will contact pioneer. ugh, I mean I did those 2 tasks separately hehe.

Reply:

Bob:

I would leave the system OFF entirely until at the very least you're sure that you put in the proper charge of refrigerant. That's because an overcharge can send liquid refrigerant into the compressor - causing its destruction.

 

Reader question: fan is blowing hot air out the sides

I had a new comparator and fan motor put on my Trane compressors/condenser outside. The fan is blowing hot air out the sides and you feel cool air on top Is it running in the right direction On 2020-07-22 by Joanne

Mod reply:

Joanne

On most units that would be backwards

New fan motor gets very hot and stalls - wrong horsepower or fusing or capacitor?

Air conditioner guy changed the fan motor on compressor, and it's getting very hot to where it starting to burn up and stall, I looked at it and it's a 3/4 hp instead of a 1/3hp and a 5.2A I stead of a 5.0A, he also deleted a little transformer and added 2 different capacitors, so is that the problem? On 2021-07-24 by TJ

Reply by inspectapedia.com.moderator

@TJ,

I don't feel safe diagnosing this one from your text alone, but it certainly sounds like there's a wiring error if not a couple of errors.

You might want to call the service manager and ask for an experienced service tech.

In the meantime you want to leave that system turned off to avoid fire.

 

Question: York YCJF42541S1A outside unit was running but the fan blades weren't

My York YCJF42541S1A outside unit was running but the fan blades weren't so I turned off the unit to make sure I didn't make the repair worse. Inside the house is warm and could have been blowing warm air. Tech came out and replaced the fan motor.

Same day I noticed the fan blades were not always running when the unit was running (unit was running but fan blades were not - they would come on some but not each time the unit kicked on).

Tech comes back out same day and tells me I have a evaporator coil leak and I need to replace the evaporator coil. Does this seem reasonable? The unit is 8 years old. Shouldn't the coil last longer than that? I don't want to spend the money if it is a capacitor. Help 2020-06-08 by Denise

Mod reply:

Denise

There is probably something here that we don't understand. I'm not sure how refrigerant leak would make the fan run intermittently.

Seems more likely that it's a wiring or control board or motor capacitor problem there may also be a refrigerant leak and which case we would have The Coincidence of two different problems occurring at the same time.

Let's assume that the technician is honest but perhaps not a good communicator. You might ask for an explanation and let me know what you're told.

Follow up:

Ok, I am not sure about the model number of my unit either. The tech's writing is hard to read. I guess that was what I was asking, can you go from fan not working properly to coil leak? I am not convinced the fan was fixed either the first or second visit.

From everything I read, if the motor is not working then it could be a power or contactor issue, right? The unit cooled fine until late last week when we noticed it being extra warm but we have had a mild spring until the last couple of weeks.

I am thinking of asking for a second opinion just to be sure before I sink money into a new coil. Anything else you can think of to ask about this situation? I really appreciate your help!

Condenser fan wiring nicked by a fan blade

Wire of my AC outside the house has been knicked by the fan. AC does not work. How to repair the damage. Thanks. (June 16, 2014) Nick

Reply:

Nick

If the wire didn't short out (which would damage equipment or trip a breaker) it can be spliced & waterproof-taped, or replaced completely.

WATCH OUT: for fatal shock hazards. Don't try working on live equipment. Hire a trained professional if you are not qualified to make this repair.

Compressor / condenser unit fan wiring: the hvac tech left wires sticking up out of my fan unit

I just had a new fan motor installed....$569.98! Also is it standard procedure to have wires sticking up from the top,,,,? These were told to me to be so he could reverse the motor if need be? - Vicky Cummins 6/18/12

I have a red and white wire coming into my house for the thermostat from the AC unit. in the furnace I have red, white, green and yellow. which wires should I connect the red and white wires from the air conditioner to? (Apr 28, 2015) Anonymous

Reply:

Vicky,

No not in my opinion. It is a poor and dangerous practice to leave live electrical wires protruding out of any appliance - it's a shock and electrocution hazard. Perhaps the tech intended this as a temporary measure to be sure s/he could correct a wiring error. But electrical wires should not be left exposed.

Anon: see

THERMOSTAT WIRING COLOR CODES

at inspectapedia.com/heat/Thermostat-Wire-Color-Codes.php

New condenser fan motor, cap, but compressor hums

Condenser fan motor, new, all capacitors, new, Works fine cools house for 1/2 hour then new fan motor shuts off and compresses hums, wait 1/2 hour and it does it all over again. help - Mike Nichols 5/2/12

my unit outside will not come on but it does inside what can be wrong - Larry 5/21/12

Reply:

Mike it sounds as if you are describing a bad compressor motor, bad starting capacitor, or wiring error, not a bad condenser unit fan motor, especially if you are dead certain the start/run caps are OK.

See COMPRESSOR / CONDENSER REPAIR where we list diagnostic articles.

Larry: same advice as for Mike. If you are sure the controls are calling for the equipment to run and voltage is present, start by checking the diagnostic articles in the order listed at LOST COOLING CAPACITY.

 

Question: risks associated with running the inside and outside A/C units to the same electrical line?

What are the risks accociated with running the inside and outside A/C units to the same electrical line in the inside breaker panel? Just had an older unit replaced by a new 3.5 ton inside air handler and outside condenser. Thanks. On 2020-08-31 by Andrew R.

Reply:

Electrical overload, loss of cooling.

 

Question: heat pump fan outside is not working

my heat pump fan outside is not working after a man put a water pump in the roof before he came water run down the wall in side. 2020-01-25 by joyce

Reply:

Joyce

From the very little we know about that situation that you described it would make sense to leave the circuit off completely for safety. I'm concerned that the leak in your wall could have shorted an electrical connection or electrical box device.

Condenser Fan Won't Stop FAQs

Condenser Unit Fan Never Stops

Why does my condenser fan run constantly? On 2021-06-13 by Kevin

Reply:

@Kevin,
Depending on:

- the cooling capacity of your system

- the air leakiness of the building

- the building's insulation system

- the building's heat gain through windows, sun exposure etc.,

- the thermostat settings

- system maintenance condition (such as a dirty air filter or dirty blower fan that reduce A/C output)

- probably some other factors

an air conditioner or heat pump in cooling mode may run continuously in very hot weather without that meaning that the system needs repair.

After that, in the above FAQs, please note the following response:

"On some compressor / condenser units the fan may run before or after the compressor motor has shut off, but it should eventually stop. If it doesn't, there is a control or wiring problem to be found and repaired.

In that case, I suspect a wiring short or a control board or relay failure at the compressor/condenser. I'd shut off the system and ask for service."

The below article will also give you more information on HVAC diagnosis (this is the home page to the page on which you posted your question).

OUTDOOR COMPRESSOR CONDENSER UNIT PROBLEM DIAGNOSIS

inspectapedia.com/aircond/HVAC_Condenser_Unit_Diagnosis.php

 

Question: outside compressor / condenser fan won't stop running

(Mar 5, 2015) Tak said:
Outdoor fan keep running even if we have the system turn off by the thermostat

(Mar 7, 2015) Susan said:
I turned my heater off and kept hearing it running. It's a heat pump and everything was frosted over. I just pulled the outside ac breaker out. What could be the problem

(Sept 14, 2015) Brent said:
My unit is cooling fine but the compressor and outdoor fan does not shut off even when I turn the thermostat to off.

Reply:

Tak

On some compressor / condenser units the fan may run before or after the compressor motor has shut off, but it should eventually stop. If it doesn't there is a control or wiring problem to be found and repaired.

In that case I suspect a wiring short or a control board or relay failiure at the compressor/condenser. I'd shut off the system and ask for service.

Brent, a search of the InspectApedia website for "COMPRESSOR WON'T STOP RUNNING" finds

COMPRESSOR / CONDENSER DIAGNOSTICS

that includes a section titled

Step 5: THE COMPRESSOR/CONDENSER RUNS TOO LONG or NEVER SHUTS OFF

Condenser Unit Fan Won't Start FAQs

Mini Split Condenser Fan Motor Sticks & won't Turn On Unless Power is Off

I have a Gree mini split unit that is throwing an error code related to the condenser fan. I. Notice that the shaft of the fan motor is sticking when I turn it manually. This sticking is preventing the fan from turning when it's on during normal operation.

I notice when I unplug the motor from the main circuit panel that sticking goes away and the shaft turns like normal.

There is no electricity going to the unit. The breaker is off and the disconnect is unplugged. Am I looking at a circuit board issue or a fan motor issue? - On 2021-02-20 by David

Reply by (mod) -

@David,

That sounds like a motor failure, perhaps a bad bearing. When power is being applied and the motor is torqued the bearing may be binding.

Also see AIR CONDITIONER WON'T START

 

Question: buzzing in the outside compressor/condenser unit

The fan want run on air conditioner outside unit. It just makes a buzz sound - Joe Russell 5/23/12

Reply:

Joe: could be a bad fan relay or start capacitor; Does the compressor itself try to start?

Hosed out the outdoor condenser unit, now it just hums but wont' run

Just bought a home and hosed out condensing unit, probably spraying water on electrical components inside. Fired up A/C and ran fine for about an hour, then it shut down. After letting it dry out a day, I tried firing up and neither furnace nor air conditioner will operate.

A humming noise is coming from the fan blower. Concerned I may have shorted out some wire which led to the fan blower. Sick to my stomach I've worked so hard on this home. On 2020-06-23 by Ken -

Reply by (mod) - humming noise from fan blower motor

Ken

A humming blower motor is often a sign of a seized electric motor or possibly a bad relay or control board - that can happen if we get electrical components wet. So sorry, but we've all fouled up something a time or to or ... even more.

If, with power off, the blower motor spins easily I'd try replacing the start/run capacitors, and
before turning power back on I'd be sure every component is dry.

Watch out: if you're not familiar with proper safe electrical work you could be shocked or killed.

Also search InspectApedia.com for ELECTRIC MOTOR DIAGNOSIS for some easy tests

Condenser Fan does not come on when heat pump turns on in heating mode

My furnace has a heat pump. When the heat kicks on the outside fan may or my not come on.

I figured this out because I could hear a funny noise from my heater. I could feel alot of heat and it was quite warm to the touch. It was overheated.

I immediately came back up and turned it off.

I left it off for several minutes and turned on and bundled up to go outside and the outside fan was humming and the fan was not running. I waited for a few minutes and as I turned to come back the fan kicked on.

This fan has always come on when the furnace kicks on. I didn't know what to do but to come back in and turn it off. Ive just had a hot water tank to burst and destroyed pretty much everything in my basement. I don't know if that has anything to do with it or not. Im really struggling because I found out my insurance isn't worth much.

It wouldn't pay for the HW-Heater or the plumber. Cut the value of my carpet in half. I don't know if they would do anything about a hot water heater and my deductible is outrageous. Im struggling and searching you tube hoping there might be something simple I can do until I can do better.

This heater sits in the same closet where the hot water tank sits. They were side by side. There was probably 4 or more inches of water running out my basement door. The room where it happened has no doors. That room is huge.I need help! Anybody have any ideas? - On 2020-12-06 by Lois

Reply by (mod) -

Lois,

That sounds a lot like an electric motor that's having trouble starting.

Particularly if a control or motor got wet from the previous event in your home it may have been damaged. Do you know if any electrical components were supposed to water or high moisture?

Fan Controller Keeps Condenser Fan From Turning On When It Should

Hello, I recently replaced my OEM fan and run capacitor after having it troubleshot by local AC repairman, who said the voltages to fan were good, so it had to be the fan (right). Fan still doesn't run. It's a 2 speed fan, so I purchased the OEM motor to replace it.

I have: Replaced motor (spins freely, OEM, correct connectors and voltages labeled), replaced capacitor, checked breakers, checked contactor, all seems good.

The only thing different I can tell is that there is a fan speed controller between the contactor and fan.

I pulled the fan connector apart and checked voltages, red lead was hot whether contactor was on or off, the other 3 leads all stayed zeroed out regardless of contactor position

Could this be a controller failure? Thanks. On 2020-06-20 by T Jones

Reply by (mod) -

Nice going TJ

Yes it sounds to me like either a wiring error (perhaps at the controller) or a bad controller.

Compressor condenser fan not working, compressor is humming, trips circuit breaker

come home to find the home hot and the condenser fan not working and the compressor making a humming noise. Took outside condensing fan off and got it freed up, oiled the bearings and it works, but the compressor is still not coming on. Whats Next? Thanks for your help. - Johnny

my A/c will run for 1/2 an hour them the home circuit breaker switch trips. A/C units seems to run properly until the CB trips. I've repeated this over several days 6 times. - George

Reply:

Johnny, it sounds as if the problem is not the fan unit but the compressor motor itself is not starting.

See COMPRESSOR / CONDENSER REPAIR where our diagnostics of that unit begin. A humming A/C compressor is unable to start; either the motor is ruined or you might just need a start/run capacitor.

George: as with Johnny's case, if your compressor unit is tripping the circuit breaker it's drawing excessive current. The motor may be running and may seem ok but drawing high amps. You need help from a service tech who will check for those conditions, or take a look at the same link we just suggested to Johnny, above

. It sounds like a component is overheating; usually a tripping CB means a bad compressor motor or a control or problem causing the compressor (or another component) to draw high current.

Follow-up from Johnny:

put hard start on and it running again thanks for all your help - Johnny

Condenser unit fan startup troubleshooting - fan starts slowly or stops completely

Ran into a very strange situation with my 3 ton HVAC heat pump. Capacitor, 240V relay both good. Windings on compressor and fan seem to be reasonable (Fan run winding 32.2 ohms, start winding 94.4, overall 125.9 ohms). Compressor run winding 1.3, start is 3.5 overall is 4.2 (expected sum of 4.8 ohm???).

When thermostat off, condenser fan runs. None of the windings are shorted to ground. When breaker is turned on, condenser fan starts up a little slower than normal then proceeds to full speed. When thermostat turned to cool, condenser fan quits and compressor turns on.

Pull one leg of compressor off and fan does not operate with thermostat on “off” or “cool” position. 24 volt ac to relay working correctly. Unit is 15 years old. Have you ever heard of similar situation ? - J.Y.

Reply: check the fan contactor, the circuit voltage and current draw when the compressor is starting; possible control board trouble?

I am sorry that I don't know an immediate fix to what you describe and no I haven't quite heard this sequence before. Some speculation and arm-waving might be of a little help though:

A condenser fan that won't stop running, won't start running, or acts weird, could also be due to a bad fan contactor switch - one that sticks on, off, or has burned contactors. And as we cited above, a fan motor that is overheating can be going off on thermal reset - those don't quite match your problem description however. But be sure that contactor switch is working ok and clean.

A slow condenser fan startup could be a bad start capacitor even though the one in place seems ok - it's cheap to try swapping in another cap, no? But you might want to look also for low voltage on the circuit. Shorts and lightning strikes and power surges can also sometimes cause symptoms like this (as can mis-wiring 240V or 3 phase circuits).

Regarding When thermostat turned to cool, condenser fan quits and compressor turns on.  if you are seeing a big voltage drop ( is there hard starting compressor motor?) and if fan is fed off one leg of that circuit, I wonder if that might stop the fan.

Does it ever re-start once the compressor gets going? Sometimes a motor will look good when tested "off" - with nothing spinning, but when parts move, a winding can open up or a connector fail.

My last arm-waving would be to wonder if the circuit board has been fouled-up.

Regarding: Pull one leg of compressor off and fan does not operate with thermostat on “off” or “cool” position.  24 volt ac to relay working correctly. - that makes sense if as often the case a 120V fan motor is being fed by one leg of the compressor 240V circuit.

I've posted this fan startup problem on the Compressor/Condenser Fan Diagnosis/Repair page - perhaps another reader will have some smarter troubleshooting advice for us. Keep me posted on what else you find - what we learn will help other readers.

Follow-Up from J.Y. - fan startup trouble traced to defrost circuit

Good morning, sir. Apparently this issue is caused from the defrost circuitry. It makes absolutely no sense to me at this point; however, when I take the black wire from the fan motor that goes to the relay (defrost circuitry, not the 240 volt relay) and put on L1 (120 Volt AC) the fan operates normally.

This really has me confused because I see no way for L1 to ever get to the fan. L2 goes to one side of the normally closed relay (defrost). The only place that I can see L1 goes is to the compressor from the load side of the 240 volt relay.

Apparently when the defrost mode is on when heating in the winter, the condenser fan stops and compressor is running while the condenser is defrosting.

While this makes sense, I was unaware of this. Once I found out that the condenser fan shuts off during the defrost mode (thanks to HVAC friend), I check the output and found L2 (which is what you would expect since L2 is on the other side of the relay from the black fan wire).

I am going to have to study the diagram further to understand how this works. Currently while I am happy to get the AC going, I am clueless to how L1 can ever get to the fan motor. Pulling the compressor wire also has an effect that I don't understand.

To help others if they ever see this:

if your condenser fan runs when the thermostat is off, and then stops once your turn the thermostat to cool, and the compressor starts, move the fan wire going to the defrost circuitry to L1 so you get 220V on the fan motor. IF the fan starts operating correctly, something in the defrost circuitry is bad - either sensor or board.

Reply-DF:

Clarifying:

On some heat pumps that use a defrost cycle, during that period the compressor runs and the fan turns off (the idea is to warm up the compressor). That would be normal operation.

If it's a properly operating defrost cycle on a heat pump, the fan might remain off and the compressor on for about 10 minutes.

If the system is operating strangely (leaving the fan on forever, or never turning the fan on - and other fan operation problems like a bad motor, contactor, capacitor, wire, etc are ruled out) then I suspect a bad control board.

But I'm confused about putting 220V on the fan circuit. Isn't your fan motor a 120V unit?

Compressor condenser is making a high squealing noise and the fan won't go on

I read all the above but I think I'm still confused. Last summer, I came home to hear my outdoor compressor unit making a high squeeling noise. I turned the AC off for the day and the noise never reappeared. Yesterday afternoon (temps in high 90's for several days)I lost air conditioning again. The outdoor compressor was making noise but the motor and fan were not running and it felt very hot to the touch.

I turned off the AC and left it off till this morning. When I turned it on, I then went outside to check compressor. Fan wasn't turning so I took a stick and manually turned the fan blades. It then started up and continued to run for about an hour until the fan stopped turning again.

I again turned the AC off for about an hour then turned it back on and the same result, fan would run for about an hour then stop spinning. Here's an observation: when the unit is off, I can take a stick and spin the blades freely in either direction. If you can help me I would appreciate it. Thanks - Don 6/21/12

Reply:

We have a separate article on diagnosing compressor noises. I found it by searching InspectApedia for "squealing compressor" - the article is titled "HVAC Noise Diagnosis & Cure: How to Evaluate Air Conditioner / Heat Pump Compressor, Air Handler, Ductwork Noises", and you can find it by clicking

on NOISE AIR CONDITIONER / HEAT PUMP in the links listed at the ARTICLE INDEX the bottom of this article .

Quoting from that article: Squeals, normal A/C compressor: Normal air conditioner compressor squealing: Some compressors emit a high pitched noise during normal operation or just at startup.

This noise should be brief and just at start-up, and will probably have always been present on the system if it's normal. More examples of compressor squealing diagnosis are in the Q&A in that article.

Goodman fan and compressor don't come on in Florida

Have a florida heat pump system...Goodman..fan and compressor doesn't turn on...

replaced capacitor...still doesn't turn on...checked all circuit breakers, etc..did find a frayed wire ( black ) that plugs into the contactor..cut the bad part out and replaced the spade connection...still doesn't work...thermo. is set for 70 degrees..temp. inside is 78 ...

seems like there is a reset or fuse somewhere that is bad...no noise or humming etc...Not sure where to go from here... 2016-10-31 by Ken C. allbsdd@aol.com

Reply:

Or could be a bad control board or relay. I'd start by confirming that there is electrical power to the unit.

Watch out: you could be killed by electric shock. If you're not trained to fool around with the compressor/condenser unit and its wiring I'd recommend hiring a service tech.

Fan won't work on the outside unit

My fan won't work on the outside unit, what could be causing this? 2016-07-17 by Ethel

Reply:

Ethel, probably the problem is one of those discussed in the article above - you're on the right page.

OF course start by confirming that the outside unit has electrical power and your thermostat is calling for cooling.
Your service tech will check for:

- a bad fan start/run relay

- a bad fan start/run capacitor

- a failed fan motor

 

Condenser Fan motor in outside unit went bad, replacement fan is different

Fan motor in outside unit went bad and installer used different fan motor than came on unit when new

Now the fan is lower in unit 2 or so inches and system seems to not cool house as easy any thoughts on this one end of season now. 2016-09-29 by Anonymous

Reply:

Anon:

If the replacement fan motor meets the operating specs of the original one it should be OK. Moving the actual fan blades inside the condenser unit might indeed change the airflow pattern enough to be worth thinking about.

For example a typical condenser fan draws outside air IN through the condensing coil around the sides of the unit and blows the heated air UP and OUT at the top of the unit. If changing the fan assembly caused some of the exiting air to blow against the upper sides of the condensing coils you'd be reducing their effectiveness.

If the condenser unit is less efficient than it was before it might have to work harder and longer. But I think your tech will look elsewhere if the house is too warm.

Hit the Condenser Unit Fan, Control Board, or Motor to Make It Run FAQs

Condenser Fan Motor on Lennox Unit Won't Start Unless I Hit It

Occasionally, my condenser fan (Lennox 13ACD series) will not fire up unless I tap/hit it the side of the unit, at which point it engages immediately.

It has happened three times in the last two weeks.

Is this worth a service call, or am I looking at purchasing a new unit? - On 2020-07-13 by Brad

Reply by (mod) - condenser fan (Lennox 13ACD series) will not fire up unless I tap/hit it the side of the unit,

Brad

Thank you for a helpful diagnostic question and kudos for already taking a great Diagnostics step.

In my experience when you can get a piece of equipment to run by tapping on it there is either a loose connection or a bad relay or control switch.

That's what I would look for first.

Compressor fan won't run unless I whack the fan blades with a stick

\My house A/C turns on OK. The outside fan will not rotate unless I stick a paint mixer stick between the vent holes and give the fan blades a shove. Then it cools fine. Is the fan worn out and has it become unable to start itself? (June 12, 2012) Donn 

Reply:

Donn: you describe a classic case of a bad start/run capacitor.

See CAPACITORS for HARD STARTING MOTORS

Helpful compressor / condenser fan diagnostics - start capacitor replaced, have to tap on the control board

I have an erratic running fan on my outdoor unit, fan not running, so replace ( Dual Cap) now fan ran like new or not at all, but the compressor motor still comes on. I checked the Dual start cap, and it check out ok once, but would fail the same test later. So I replace the capacitor (exact - OEM) and the compressor motor still came on, but not the fan.

However, (the strange part) while thinking what was next, I lightly tapped on the top of the circuit board, in the area of the Fan relay ,and there others side by side, ( not for any reason ) just pondering.

Then the fan started up and ran like new. However, when the unit shut down, and restarts the fan may run great or not. When it does not, I go outside and lightly tap the top of the circuit board in location of the fan relay, the fan starts full speed, and I have cool air.

This would make a little sense if it were a (mechanical relay), but its solid-state- no contacts there?

Go figure, maybe I need to troubleshoot the entire concert board, however everything is plug and play now days, and it is very unlikely I could get a component if I where to find it. I know a bit verbose, but I feel it could be so many things, so any suggestions would be appreciated.
Thanks,
Brian

Reply:

Brian you've done some excellent diagnostics. Your description suggests that either there is a loose wire or an actual loose component on the circuit board in the compressor/condenser unit. Not only is having to tap on it not a reasonable way to live with air conditioning, it could be dangerous, risking a shock.

If you can't see and fix a loose wire or connection to the board or to other wires nearby, I'd consider replacing the circuit board. In the article above where we list types of compressor/condenser fan problems we include this topic.

 

I took a stick and pushed the fan blades and they started moving

I have a 220V condenser fan motor that is running 1/2 speed backwards when the AC is off. When AC turns on the motor changes direction (runs forward) but still only at 1/2 speed. I have replaced the contactor and dual start capacitor and that did not have any impact on the symptoms. (Sept 17, 2014) Anonymous said:

I hope someone can help me fix my goodman 3 ton heat and air unit heat pump.

The trouble I'm having is I heard this clicking noise like the fan trying to come on, but never did until I took a stick and pushed the blades and they started moving than I went inside the house and the air coming out was not cool could anyone tell me where to start checking, I,m going to try to fix this myself . (Oct 6, 2014) Diane Feltner said:

Reply:

Diane,

The problem could be a bad fan start relay or (probably) fan motor capacitor or quite possibly something else - I can't tell much from your note.

Frankly you'd be safer hiring a trained HVAC repairman. Someone with experience can not only hone in quickly on the trouble but they're more likely to have test tools, gauges, refrigerant, and parts needed.

Condenser Unit Fan Won't Keep Running FAQs

Reader question: AC turns off outside and doesn't come back on until I switch the AC off

My heat pump has a similar issue only in reverse. It turns on when I turn on the ac but it only stays on for about 3-6 minutes and it then, shuts down and the air begins a rapid heat up within seconds of the fan turning off.

The fan turns off outside and doesn't come back on until I switch the ac off and wait at least an hour or so n but it is still blowing air in the apartment. 2020-07-13 by Jon Christian

Mod reply:

Jon

I think you are describing the case in which the outdoor compressor condenser unit is shutting down shortly after startup. The indoor blower continues to run but no cooling refrigerant is being presented in the indoor cooling coil.

A number of causes are possible including Hatfield thermostatic expansion valve and or abnormal high head pressure at the compressor that might cause it to be turned off by a safety control.

Do let me know what your service repair technician says

Air conditioner runs for a couple of hours then the condenser fan will suddenly stop

I have a nordyne model js3bd-030k that after been running for couple of hours the fan will suddenly stop even when you still feel the air circulating and out of the vents any body would know what is causing the fun to act this way any help will be greatly appreciated. thanks for any help

Reply:

Mario, the air conditioner or heat pump diagnostics on this page apply to the outdoor fan found on the condensing unit. But as you are talking about stoppage of air coming out of your indoor supply registers, you will want to take a look at the diagnostic notes on the indoor air handler or blower fans (the indoor unit that circulates air in the building) -

see BLOWER FAN OPERATION & TESTING.

Question: Compressor / Condenser fan stops working in hot weather - replacement motor also failed

I have an ongoing problem with my A/C unit. It is working until it gets very hot (over 100 degress here in Texas) and stop blow the cold air. I called a tech last year and he replaced the fan motor twice, once with a same model and next with a larger fan. Again this year I'm having the same problem. Any idea what could be the soulation? - Abby

Abby I am having this problem and I can wait untill the late evening when the temp drops or the unit becomes shaded I can reset a swithch and it turns it back on and it will blow cool air untill the next day when it does the same again. I suspect it is the overheat switch because mine is always popped - Ernie

Reply:

If a fan motor is replaced repeatedly I'd ask the service tech and service manager to do some further investigating as something else may be destroying the fan motor. Examples of other problems that can ruin the blower fan or condenser fan motor include:

- an improperly-sized start/run capacitor that fails to drop the start capacitor out of the circuit once the fan is running can burn up the fan motor start windings

- consistent abnormally low supply voltage

- a mechanical problem stressing the motor such as a blower assembly bearing or shaft problem or improper fan/blower connections or mounting

Heat pump is not blowing cool air - the condenser fan won't keep running

have a heat pump not blowing cool air. The condensor fan will run for about 1 minute then shut off and not start again for a few mins.

Once it starts up the same thing every time. This unit says it should be at 300 psig for both high and low pressure but when i put the gauges on it im only getting 155 on both sides. what could be causing this.

I suspect that the unit has a low charge and is causing the fan to trip or the compressor may not be pumping, im not sure. all i know is that when my gauges are on it they do not change in pressure when i engage the contactor - Cox HVAC 5/26/12

Reply:

Your system compressor is not continuing to run, nor is the fan. Check the start/run cap and the control board as well as the relay.

Question: Common causes of a fan motor intermittently cutting off

I have a trane heat pump. The fan motor and capacitor have been replaced.

The fan is still cutting off and not cutting back on. Got up this morning and it was off, but the unit was still running. It had gotten down to 62 degrees. Had to turn the unit off for about an hour. When I turned it back on the fan came on. What else could be wrong with it? 2019-11-25 by Chris

Reply:

Chris

Common causes of a fan motor intermittently cutting off include

- loose or bad electrical connection

- defective fan control relay or control board

- overloaded motor, including possibly low voltage supply that could affect even a new motor

- improper installation, binding motor or fan assembly (also overloading the motor)

You might also find by searching this website our article on ELECTRIC MOTOR DIAGNOSIS

Common Condenser Unit Fan Diagnostic Questions & Answers

Question:

My condenser fan is a trane fan03652 or replacement fan04690. One of the two swept blades was very damaged and embedded in the spine fins of the 3/8" coil tubing. The coil was not penetrated & maintains pressure. Upon testing the condenser motor, it runs and spins true.

The only culprit I could pin this to was that the framing the motor & fan are supported by, was that of the four screws that secure this assy to the chassis, 3 of 4 had missing spacers.

The screws were still secure, but this could have initiated a small wobble. This is speculative.

The four screws of the fan motor to support frame were still tight, as were the four bigger screws attaching the framing to chassis (minus spacers). Am I barking up the wrong tree and should I be looking elsewhere? 2020-08-03 by Wayne

Mod reply:

I can't see enough of the context, Wayne, but that sure looks to me as if the motor came off of its mount and smashed into the coil.

 

New coleman control board keeps cutting off

i bought a new coleman control board for my heat pump in the fan is only running for 3 min than cut off. 2016-09-14 by deena edwards

Reply:

Deena

One can but guess that as the control board is new and guessing that the fan relay is on the control board the trouble is elsewhere. I expect your service tech will check voltage, loose wiring, fan motor start/run cap, fan bearings.

Follow up:

I straight wired it in it runs good

Reply:

Good diagnostic - especially if nobody gets fried.

That suggests a bad fan control, relay, or control/relay wiring.

What is the purpose of the outdoor condenser unit fan?

What is the purpose of the compressor fan and its fan blades? - Mike

Reply:

Mike the reason you see a fan on the compressor/condenser unit comes from the need to transfer heat from the refrigerant system into outdoor air. Refrigerant gas is pumped from the indoor cooling coil through the outdoor compressor motor. The compressor produces high-temperature high pressure refrigerant gas.

That gas then flows into the outdoor condensing coil - it looks sort of like a car radiator with finned tubing. As the hot gas flows through the condensing coil, the outdoor FAN blows outdoor air across the hot condensing coil

That cools the gases inside the coil back to a liquid state and at the same time is transferring heat into the outdoor air.

The liquid state refrigerant can then return to the cooling/evaporator coil back indoors in the air handler where it is used to cool indoor air.

The "magic" of an air conditioner or heat pump is that by INCREASING the temperature of the refrigerant gas to a high level outdoors we are able to move heat INTO outdoor air even when the outdoor air is warmer than the indoors of the building.

Where can I find a video on how to install a FASCO condenser fan?

where can i find a install video for a fasco 1/6HP FLP1.3 230V 1075RPM Center AC unit - Richard 10/16/11

Reply:

Richard, Fasco provides replacement and OEM electric motors including for HVAC equipment. You can contact Fasco directly through their website at: fasco [dot] com - you'll find that the company will be glad to assist you with installation manuals, guides.

Question: air conditioning drags voltage

The Air conditioning drags voltage and almost turns off other appliances when compressor attempts to start up. And if used on a generating set it seems to power off the generating set, though testing the compressor with a digital multimeter it seems it's still functional, or I suppose so
Please advice on what to do, thank you 2020-06-04 by Nsisong

Reply:

Nsis

Usually drawing high amps is a sign of a failing motor

Question: Humming fan motor

Changed compressor starter capacitor but not the dual run capacitor. Now the compressor comes on (freon line gets cold) however; the condenser fan is not running but humming.

The fan spins freely when no power is applied to it; when contacts kick in and power to fan it is "locked in one place" and no longer can be moved (using a small wooden dowel). I ohmed the 3 motor windings and they add up correctly. Could this just be the run capacitor? Is this more likely the fan bearings? 2020-06-11 by Fred

Reply:

Humming fan motor usually means either a bad starting cap or a seized motor.

Which way should air flow through my outdoor A/C or heat pump condenser unit?

From TC: Instead of blowing air out of the top my fan is sucking air in from the top and blowing it out of the side of the outdoor unit. I have 3 units same brands and 2 of them are blowing and 1 is sucking. I did have to replace the capacitor but I marked the wirers and pput them back the same. is this a problem?

Reply: most but not all A/C condenser units blow hot air in at their sides and out at their top.

TC, models of compressor/condenser units vary in which surfaces of the unit are air intake and air exhaust. As long as you don't block the intake and exhaust you'll be ok. But looking at your condenser unit design, typically you will see that outdoor air is drawn through the condensing coil first and then exhausted by the fan - the fan is usually "pulling" air through the coil not pushing it in that direction.

However, your fan motor could be running backwards. See "Steps to diagnose and repair a condensing unit fan that is running backwards" just below.

Steps to diagnose and repair a condensing unit fan that is running backwards

From Brent K: I have a Samsung Ductless 3 split A/C unit. The other day I noticed the condenser fan running backwards at a slow speed.

At the compressor/condenser unit, air should enter the cooling fins and drive out through the fan. When the condenser unit was first turned on the fan ran clockwise - in the right direction. But when the high speed kicked in the fan motor came to a stop then started to reverse direction.

When the low speed kicked back in the fan motor came to a complete stop until the high speed kicked back in then it started turning in reverse again.

The cooling ability inside the house also diminished [as it would be if the compressor/condenser is having trouble cooling the refrigerant back to a liquid].

Basic fan motor diagnostics:

I checked out the fan motor windings with an ohms meter. They didn't match what was published in the service manuel but there was an acceptable resistance level similar to other fan motors I have come across.

The controller card [circuit board] checked out OK

with 220V on the pin for low speed and when the condenser coils heated up the high speed kicked in and the high speed pin had 220V there. Good I thought the controller is working.

Next I looked at the run/start capacitor - found a bad motor capacitor!

The capacitor was a small black plastic block not one of those oval or round oil filled ones. I disconnected the leads after discharging the capacitor and checked it out with my multimeter set to capacitance.

Sure enough the meter showed nil not the 4uf I was expecting.

I called around to motor repair shops (HVAC shops sometimes give me a hard time and found a replacement 4uf 450VAC start/run capacitor for $11.00 CDN. Installed it and not the fan runs properly on low speed and high speed.

So my High School electrical training and 1 hour of diagnostic work saved me a bundle

If there had been a controller or refrigerant problem I would have called in a HVAC tech. - Brent K. 7/26/11

Question: right motor for condenser fan

My compressor fan motor went bad. OEM was RPM 840/2SPD. The replacement was a 1075 RPM. Unit runs for about 30 minutes and shuts off. Could faster motor moving too many CFM be insufficiently cooling compressor and how?

Reply: swapping out a 2-speed motor for a 1-speed may leave control wiring incorrect at an indoor air handler - are you sure you're talking about a condenser unit fan?

LD Neal

OEM was RPM 840/2SPD looks like a two-speed fan motor; if you replaced it with a single speed unit, and IF the original wiring was using two speeds, the new fan would indeed be acting differently.

But you are describing the condensing unit fan. More air providing more cooling at the condensing coil would be an improvement in system efficiency and I'm not aware of a case where it would be a cause of insufficient cooling.

Unless ... it's not wired properly; if the fan is not running when it should, the result would be lower system efficiency and even risks compressor damage.

Could an improper dual run (start/run) capacitor cause the evaporator coil to frost or ice up?

A tech replaced the dual run capacator on the outside unit of my heat pump system. The fan would not spin and he needed help over the phone to get the unit running again. Could an improper installation of the dual run capacator cause frost and icing? Previous to his visit I never had a problem with frost or icing. - Mike 5/24/12

Reply:

Mike, maybe in some way I don't fully understand. The fan on the outdoor comprressor/condenser cools the outdoor half of the system and thus permits condensing high pressure high temperature refrigerant back to a liquid form.

One would think that if the refrigerant didn't condense back to a gas it would not be properly metered into the indoor cooling coil and I'd guess that the result would be reduced cooling, not more cooling or excessive cooling and icing at the coil.

Usually an iced evaporator coil (cooling coil) results from

• slower air flow across the indoor coil because of a dirty air filter or fan unit or an indoor blower fan that is not working properly
• a problem with the refrigerant metering device (TEV)
• low but not zero refrigerant in the system

In the link at the ARTICLE INDEX the bottom of this article under COOLING COIL or EVAPORATOR COIL see the

article FROST BUILD-UP on AIR CONDITIONER COILS

 

How would I know if the condenser fan motor is bad?

How wolud i if the fan motor of the condenser bad. I checked running caps and its good fan blade are good. - Johnny 4/11/12

Reply:

Johnny,

If with power off the fan motor does not spin easily the motor or fan bearings are seized; but a motor could spin but not start if an internal winding has shorted or has opened.

Check to see if voltage is present at the fan motor wires. If voltage is present and if none of these steps will turn the blower fan on, and if you are certain that the motor starting capacitor is good (see CAPACITORS for HARD STARTING MOTORS), then we suspect that the motor may be seized.

If the fan blades spin but wobble, or if you can move the fan shaft up and down or back and forth where it emerges from the fan motor, then the fan bearings may be bad, causing wobbling and even binding of the motor assembly.

If the fan spins freely, there is no loose fan motor shaft play, and no fan wobble, checking the capacitor or even swapping in a new one is one fo the first repairs a tech will try as it's so easy and cheap.

On some fan motors that don't use an automatic-reset internal thermal overload control, there may be

a ELECTRIC MOTOR OVERLOAD RESET SWITCH that has tripped off.

See VOLTAGE MEASUREMENT EQUIPMENT for a description of tools used to detect the presence of live electrical wires & devices and for the measurement of actual volts or amps - a step that you'll need to take with the motor out of the unit for testing.

BLOWER FAN NO START / NO STOP - describes weird blower behavior can also be diagnosed and fixed - this article provides a detailed list of things to check.

 

Compressor fan motor began to overheat

I have a heat pump, Its been running fine in 100 degree weather. Just recently the fan motor began to overheat and go off on overload. I replaced the fan motor and am still having the same issue.

When the new fan first started, I thought "yeah", but i began to smell a heater smell coming from the top of the condensing unit. I'm not sure if the crankcase heater is on or not. What could be causing this? - Ethel 6/25/12

Reply:

I'm not sure, Ethel, but you've made some excellent guesses. A fan motor that has a bad start/run capacitor may have trouble starting and may overheat the motor, as well as the other ideas you suggested. And a motor not properly mounted, or with a bearing that is binding, can also overheat. I think a savvy tech might also check for abnormal voltage level if everything else checks out ok.

Also check that the fan bearings are not binding, causing the motor to overheat.

AC unit stopped putting out cold air - is there a reset switch?

After returning from vacation where we turned off the ac, (and water)when we turned the ac back on one of the two units, stopped putting out cold air. after going thru this awesome website, i may have found the problem.

The condenser fan outside does not come on, so i used a stick to make it run, and it did ! thought i fixed it. but the fan speed was slow compared to the other unit and the air coming out was not warm like the other unit - and then within a few minutes the fan turned off again.

The fan motor is a Emerson - Part # 37L7401 - if it has a reset switch then i will try to figure out how to get to it ( i am not very handy - not sure how to remove the cover to get to the fan) - do you know if this motor has a reset switch ? The other thing i learned from the website, is that the problem could be the capacitor, not sure how to replace that, but will cross that bridge if neccessary.

If you could please give your opinion on what is the most likely fix for this problem i would greatly appreciate it. thank you. Again this website is awesome ! (July 15, 2012) Sean said:

Reply:

Sean if the fan spins freely with power off but won't start and run on it's own the first thing most techs will do is swap in a new start/run capacitor. It's worth a try. If you're not familiar with electrical wiring, as it can be dangerous, even fatal, I'd hire a professional.

 

Cold weather problems at the compressor/condenser

The temp outside today is 0, and though I hear the fan in the furnace running, and air is coming out of the registers but there is no heat. I check on the heat pump and there is ice all around the base (from concrete onto bottom of pump). Perhaps the fan blade is frozen?

Should I pour hot water on it? Does it, as you have stated in one of your responses, have a defrost cycle and I should check in a quarter hour if it is running again?
(Nov 27, 2012) Rob Munn

Reply:

Rob,
At such low outside temperature I'd expect your heat pump system to have switched to backup heat mode. Is your backup heat not working?

 

Question: compressor/condenser trips circuit breaker

My 4 ton Bryant unit does both AC and heating.

One of the two side by side breakers indoor often trips - I think the tripped one controls the outdoor unit because the fan for indoor air circulating still runs. I reset the tripped breaker, and it goes for another day or two, then trips again. What kind of problem is that?

Reply:

Gary,
Breaker trips in response to an overcurrent. A shorting wire, relay, or control can cause the problem, but more common is a failing compressor motor that is hard starting, thus drawing high current a startup. Ask for help from a service tech. S/he might try a hard start capacitor kit to see if that buys some time.

AC compressor / condenser fan won't run or is slow starting

You are all way more qualified than myself. I'm trying tp repair a small mini bar fridge for my girlfriend. When it comes to cuircuit boards im lost I opened the thing up and found that one of the twp green cuircuit boards makes a clicking noise (like an electric fence box, but only faster)...

I'm looking at all these small capasotors and little resistors and can figure out what the hell to do...

Can anybody give me some advice.... i dont wanna go to an electrician... i wanna try fix this at home and learn something...

obviously need some advice tho... and you ppl seem to know what your talking about. any advice would be greatly appreciated. thanks. Rob (Jan 6, 2013)

My fan coil starts only when thermostat on heat but fan does not start when in cool. External unit fan and comoressor starts regularily.
It can not be the capacitor neither the fan since it starts when heat. What can be the problem? The fan unit is Carrier model Fa4Nc048. Thank you (Jan 13, 2013) Ruccardo

The fan on the outside compressor unit for the heat mode seems to be coming on late as steam comes from it for quite a long time before the fan comes on.
Is this normal or is there a control circuit adjustment for this.( Jan 13, 2013) Ernie

My outside fan is making a very loud noise and barelhy turning. What do I do? Nathan (Jan 14 2013)

my fan outside broke loose and is just hanging there with a bent blade...the unit shut off - Anon

Reply:

Watch out: I would turn power off and leave it off until the fan assembly can be replaced. Else you're risking more-costly damage to the outdoor compressor/condenser unit or even an electrical fire.

Fan blades actually ripped off their mount

What would cause the fan blades to actually rip of their mount two ripped off and the unit was vibrating a lot. It has done some damage on the inside walls will this have to be replaced too. - (Mar 2, 2014) Bill

Reply:

Bill:

A loose fan mount or a bad fan bearing could do what you describe.

Also check the voltage level

 

Compressor outside your home supposed to run when you turn the heat on?

Does the compressor outside your home supposed to run when you turn the heat on - (Nov 10, 2015) Cc said:

Reply:

Yes, if it is a heat pump and if the outdoor temperature is not too low.

Not If your compressor condenser unit is only supporting air conditioning.

Not if the outdoor temperature is so low that your heat pump cannot operate. Then you will be on back up heat.