A/C or Heat Pump Fan Condenser Unit Fan diagnostic questions & answers - FAQs 2:
More questions & answers help diagnose problems with the air conditioner or heat pump condenser unit fan
This series article discusses the diagnosis and repair of problems with the outdoor compressor / condenser fan and fan motor, including fans that wont' run, fans that run at slow speed, and fans that won't stop running.
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Avoid confusion between the indoor blower fan and the outdoor condenser fan: the compressor / condenser fan is in the outdoor unit and is used to cool the outdoor condensing coil. If you are troubleshooting the indoor air handler that delivers cooled or heated air through the duct system and supply registers, see BLOWER FAN OPERATION & TESTING - home.
On 2017-04-14 22:57:10.566120 by (mod) re: why the technician intalled an "emergency" capacitorI suspect that the technician installed a "hard start" capacitor because the standard cap was having trouble starting the motor.
On 2017-04-14 16:03:57.305894 by eddieoI just would like to know the reason somebody instead of just change the bad capacitor. He installed an emergency capacitor?
On 2017-04-11 23:07:19.864719 by Anonymouscondenser making hum noise, fan not working
On 2016-12-14 02:30:51.867149 by Jaron
Hello. I have a Rheem RBHP-24J18S air handler that has me pulling my hair out. One night I noticed only the blower was running with no heat coming out of the vents. The next day I climbed in the attic to check things out but didn't notice anything out of the ordinary. After some research I noticed the most common problems were sequencers, control board, and thermostats. I actually had a new thermostat and control board for a spare so I changed them along with the sequencers.
Then set the heat on auto to start the cycle and the blower came on and a few seconds later the air began blowing out the vents harder and warm. Everything seemed to be worked fine but a few minutes later the air flow slowed down and it was blowing cool air. I went back to checking things and found the defrost control switch was failed open so I changed it along with the watt restrictor switch. Now I don't get any heat at all just seems to be the blower blowing cool air.
I checked both sides the transformer and getting 24V and 240V and getting 24V going to the control board. I also noticed after turning on the AC that after the cooling cycle is over and the compressor shuts off the blower continues to run for a minute or so...like the heater should do after the heating cycle is complete. Any help solving this would be GREATLY appreciated!
On 2016-10-14 12:00:01.474735 by Anonymous
We recently purchased a Condo in Florida with the Condenser Unit located in a small Utility Closet on the Lanai. The unit has a 24" wide x 14" high sheet metal box and 4Ft X 24" round exhaust elbow mounted on top of the unit leading to the vent on the building wall. The noise from this 6 year old unit was unbearable.
A/C Company said everyone here has the same complaint and that we have to live with it. Wrong answer. I installed a Compressor Blanket, cut a 10" hole in the side of the Sheet Meal Box and installed a 10" Duct that vents to the outside. What a difference. Exhaust air flow is no longer restricted and we can sit outside and have a conversation.
On 2016-09-30 00:04:04.999639 by (mod)
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.
On 2016-09-29 09:04:10.307435 by Anonymousfan 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 seams to not cool house as easy any thoughts on this one end of season now
On 2016-08-16 18:38:50.005578 by (mod)Well absolutely is a pretty strong word from a nervous technician.
On 2016-08-16 17:03:29.761040 by Anonymous
We recently had our "Start capacitor" replaced on a 9 year old Trane HVAC. 3 days later, unit stopped cooling and technican says "compressor is shorted to the ground". When asked if the start capacitor replacment could have created any issue with the compressor shortage, he said "absolutely not".
That seems inconsistent... If the starter capacitor is a "energy booster" to the compressor, how could it be completely unrelated? So my question is, could/is it possible for a new start capacitor install create an "energy event' which would cause the compressor to short out? The tech said there was no way they could be related technically, Just need an HVAC genius to provide their insight. I would appreciate it. I'm looking at 2400 to replace compressor or 7K for new unit.
On 2016-06-26 13:15:06.140782 by (mod)Simply elevating a compressor/condenser up a bit would not in itself cause it to fail to operate.
On 2016-06-26 12:54:15.918307 by ThedevotifamilyWe lifted our compressor fan and placed blocks underneath so we could pour a concrete slab and now it won't kick on but the indoor unit is working. What do I look for?
On 2016-06-24 17:33:23.890492 by (mod)If the replacement cap didn't give more than 8 hours of running I suspect that the motor is failing; keep in mind that some motor problems such as a winding that opens when the motor is spinning, can be hard to find. Search InspectApedia.com for ELECTRIC MOTOR TEST to see some diagnostics.
On 2016-06-24 12:37:01.315352 by jesterdanCondenser fan wasn't running. Read out the motor, Appeared good, replaced the run capacitor, came back to life for 8 hours and the fan stopped again. Any ideas?
On 2016-06-20 10:38:47.510242 by (mod)sounds like a bad relay, control, or shorted wires.
On 2016-06-20 10:35:55.094367 by AnonymousThe blower fan on my central unit runs intermittently even with thermostat off ... The unit runs fine but this motor runs intermitently even if unit is off at thermostat... Changed thermostat and capacitor .. No help...
On 2016-06-17 02:53:35.521558 by (mod)Nice going, Jay.
On 2016-06-17 02:16:17.718233 by JayThanks again for the help Daniel, That is exactly what I did Today and after cleaning and lubricating the old motor it still cut out after a while just took longer. Went to the supply house and got a new motor. I test ran it out of the unit and no more cycling. Must have had a shorted or open turn which caused the old motor to overheat or open up. End of story, I am ready for hot weather, maybe I get another 10 Years out of it!
On 2016-06-16 14:40:57.051014 by (mod)Jay often we'll test the motor out of the unit by wiring it directly; even before doing that, if the motor shaft doesn't turn easily that's an indicator of a mechanical problem; electrical motor problems can be subtle as a winding may only open when a motor spins. Search InspectApedia for ELECTRIC MOTOR TESTING to see more suggestions if you like. DO keep me posted.
On 2016-06-15 22:31:07.693676 by JayThanks for the help Danjoefriedman, Must be the motor itself, Think I'll just replace both and see if that fixes it.
On 2016-06-15 22:12:58.113172 by JayCap seems to be OK too, On high scale of the simpson (100000ohm) get full deflection then infinitive . When I reverse the leads it is the same , no short to case. Don't see much on the 10K scale.
On 2016-06-15 21:57:25.017112 by (mod)http://inspectapedia.com/electric/Motor_Capacitor_Tests.php
On 2016-06-15 21:52:49.112639 by Jayconnections look OK nothing loose & full voltage all the time, how can I check the start /run Capacitor?
On 2016-06-15 21:46:59.911917 by (mod)Check for a loose connection or a bad start/run capacitor.
On 2016-06-15 21:15:39.874786 by JayHi I have an old Williams AC unit Has been working fine for about 15-20 Years. When I started the AC this Year, the outside unit Fan and compressor started up OK then after 20-30 seconds the fan shut off while compressor kept running. Then the fan started again for some seconds and quit it just kept cycling. It is a 220 fan motor and the voltage stayed constant on my Simpson. What can I do?
On 2016-04-01 15:10:20.705719 by (mod)I can only guess, anon that someone thought the motor needed protection from weather - normally the outdoor A/C compressor/condenser is left exposed to the elements. DO NOT TURN ON this motor while it's covered in plastic. Overheating or jamming up a motor or fan can cause a fire.
On 2016-04-01 14:36:30.122698 by Anonymousthere is a black plastic bag on the motor of my outdoor AC unit. Why
On 2016-03-06 22:19:58.499430 by (mod)Kevin
On 2016-03-06 03:13:12.744343 by KevinMy condenser fan motor shaft has up and down play but the amp draw is good. Is the fan motor still bad?
On 2016-02-06 16:00:36.577074 by (mod)Yes if you have a heat pump and if outdoor temperature is above the heat pump's lowest operating range.
On 2016-02-06 by Dave
When I turn my heat on my condenser comes on, Is this normal ?
On 2016-01-24 by (mod)
I would turn on backup heat if it's not on automatically, then call or repair.
On 2016-01-23 by Marie
Hi, I have a honeywell heat pump and the outside fan doesn't come on the inside heat is running, should i turn the inside thermostat to emergency heat
On 2015-12-08 by (mod)
The problem may be a start-run capacitor on the fan motor, or a bad control or relay.
Search InspectApedia.com for STARTING CAPACITOR to read details.
On 2015-12-07 22:57:05.150250 by keith Hwhen I turn my a/c unit on the outside fan starts spinning and about 1 min later it slows down and like 10 seconds later it cuts back on running the way it should. it did it off and on. the air inside never gets cool enough to cool the place down.
On 2015-11-17 02:25:55.225367 by (mod)Diane
On 2015-11-16 17:17:49.780508 by Diane
My AC/Heat unit runs erratically. It runs perfectly on heat/or cool then it quits working. When it quits working the thermostats controls-heat,cool and even fan or auto fan will not work. This may last for hours or days ,then it will start working again. I have had a highly recommended service company come out. First they said it was wired wrong, when they left it was working, but within an hour it quit working. When they came back they said it was the thermostat and put in a new thermostat and a third time with another thermostat. It worked for about 15 days and then started working erratically again. Now they want to replace the main board. Any suggestions? thanks
On 2017-03-15 00:36:37.553202 by (mod)Readers: if you don't see the information you need, just post a comment or question and we'll reply asap.
On 2017-02-05 15:23:23.043828 by StewartI replaced my condenser fan motor this summer. Now that winter is here I noticed my unit is not defrosting as it should and ices up. Couple things I noted. The fan is running in the right direction. The fan does shutdown when the condenser unit shuts down, The fan continues to run during the defrost cycle and I am not sure if this is correct. Should the fan be off on the defrost cycle? What would be the cause to it continuing to run?
On 2016-10-31 21:06:32.532990 by (mod)Or could be a bad control board or relay. I'd start by confirming that there is electrical power to the unit.
On 2016-10-31 20:21:13.279310 by Ken C. firstname.lastname@example.orgHave 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...
On 2016-09-14 18:44:57.504933 by (mod)Good diagnostic - especially if nobody gets fried.
On 2016-09-14 17:41:54.067492 by deena edwardsI straight wired it in it runs good
On 2016-09-14 17:35:19.950707 by (mod)Deena
On 2016-09-14 17:20:35.206886 by deena edwardsi bought a new coleman control board for my heat pump in the fan is only running for 3 min than cut off
On 2016-08-30 04:02:11.060454 by Anonymouscondenser fan is very noisy i have replaced the fan and motor and i have leveled the unit but condenser fan is still very noisy
On 2016-07-26 22:33:56.831704 by (mod)Anonymous,
On 2016-07-26 13:16:39.471642 by AnonymousI see peoples problems, where is the answers?
On 2016-07-17 15:43:52.333809 by (mod)Ethel, probably the problem is one of those discussed in the article above - you're on the right page.
On 2016-07-17 14:15:24.060053 by EthelMy fan won't work on the outside unit, what could be causing this?
On 2016-07-04 16:49:38.371360 by (mod)OF course: just turn off power to the unit while you are waiting for repair.
On 2016-07-04 05:21:13.270721 by Nancy PierceThis unit isnt working to cool the house, but it is putting heat into the house. You can hear the fan by the blower running constantly. Is there a switch to shut it off or can i disconnect wires. Help im getting sick and dust is also being blown in.
On 2016-07-04 05:14:33.082093 by Nancy PierceThe blower fan inside the furnace keeps running and its putting heat into the house when its 80degress out.
On 2016-06-17 22:26:50.625774 by TODD CohenMy central heat and air stopped working I had to look at it he said it could be capacitor do I change the capacitor the same Wilson on fan but when I put it on AC it blows breaker could I have a bad capacitor or is there another problem
On 2016-06-08 05:44:17.228357 by hank .wallaceCan I safely run a 55+5 uf MFD fan start capacitor in the place of a 30+5 uf MFD both at 370 VAC or will the 55 damage the compressor?
On 2016-06-06 11:29:55.319996 by Anonymoushusband put screen over top of fan to prevent sticks/leaves from falling into heat pump unit. will this cause damage to unit?
On 2016-04-30 14:37:07.126777 by chrisheat pump condenser fan will run for a few minutes and shuts off,the fan is red hot but won't operate. in the cooling mode the heat pump blower motor operates and blows air but the condenser fun won't run.
On 2016-04-24 13:06:13.931355 by AnonymousMy heatpump unit outside is not working right. When the temp gets above 80 the blower that moves air though the house stops working. If I turn off the beaker for about an hour and then turn it on the unit runs normal I've had tech out several times and can't fix this. This is a Trane system about 2 years o!d. What can I try?
On 2016-03-03 18:20:22.808382 by (mod)The fan motor is now probably shot - or its start.run capacitor is shot. Leave it switched off until that's reparied. Meanwhile you're on backup heat.
On 2016-03-01 14:35:18.913705 by cathyThe fan outside our unit has quit running a month before I heard a little hum for a few seconds every once in awhile now that breaker is tripped we put it back on and it tripped the breaker again so now the breaker is off the heat works fine but the blade is not turning outside could you help me with that please
On 2015-11-06 17:33:12.037313 by (mod)It sounds as if a switch remains off or is not functioning.
On 2015-11-06 00:21:06.341221 by AnonymousOutside unit fan will not come on after my husband cleaned the outside unit coils. He pulled the outside switch to cut the power but he also said that the compressor and fan were off before he pulled the outside switch. Help, he's an operator not an a/c man.
On 2015-09-10 06:29:06.707779 by Nikhil PrasadMy AIR COOLER (NOT A/C) runs for sometime and then its fan and water pump shuts off but the auto swing keeps running.
On 2015-08-20 10:55:32.450253 by Sridhar3 months old General AC, out door unit fan running slowly(70%) with little humming. In the first 2 months it worked perfectly.
On 2015-08-16 17:48:13.405230 by (mod)Your HVAC service tech will perhaps check current draw and look for signs of a failing compressor motor.
On 2015-08-15 01:02:24.006362 by MalcolmI changed the capacitors in two units and in the addict it worked for a while and then they one went out and the fan stop spinning in the unit. I got a hard start for the other and it worked for a while then the fan stopped spinning in it as well. Neither prior to the capacitors were removing hot air. What should I do next?
On 2015-06-12 11:29:33.583360 by (mod)If a motor is overheating that ought to be discoverable by some basic electrical tests of current draw;
On 2015-06-10 22:17:20.312530 by anonHello, here is my problem that hasn't been fixed even after a few technician visits.
On 2015-06-09 19:08:36.658500 by (mod)Look for a bad start-run capacitor.
On 2015-06-09 18:18:56.608770 by LillOutdoors condenser unit starts only after manually spinning the blades a few times. Once it is off for more than an hour the same process must be repeated to make it start again
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