Mini Split-system air conditioner & heat pump FAQs set #3.

These FAQs help diagnose problems with split system or ductless air conditioner and heat pump systems.

This article series describes split system air conditioning & heat pump systems. We review the major system components, switches & controls, and typical applications for split system cooling systems.

Split System A/C & Heat Pump System Diagnostic FAQs-3

A split system or "ductless" air conditioning (or A/C & heat pump) system dispenses with duct work entirely, using a wall-mounted indoor evaporator/blower unit and a separate outside compressor/condenser.

These split system A/C install, troubleshoot, repair FAQs were posted originally

at SPLIT SYSTEM AIR CONDITIONERS & HEAT PUMPS - - check out the diagnostic and repair procedures suggested there.

On 2018-12-31 by (mod) - if the fan won't run it's often because the heat Source isn't operating

Typically when we are in heating mode if the fan won't run it's because the heat Source isn't operating.

The problem is probably not the fan but the fact that your heat pump isn't able to run or the temperatures are so cold that the backup heat is being called on and that's not running.

On 2018-12-31 by Marcos

I have a ductless split system ac & heat. The unit turns on fine ac works but now that i want to switch to heat the fan won't run at all it just stays in heat mode without the fan running. Any suggestions on how to make it work or why the fan won't run?

On 2018-11-08 by (mod) - error codes flash in rainy weather

my guess is that an electrical connector or circular control is getting wet. But it would be helpful to use the instruction manual to look up the flash code. Let me know

On 2018-11-07 by Peter

Why would my Panasonic mini split multi-zone systems flash an error on all three wall units when it rains, then return to normal operation after the rain.

On 2018-01-09 by (mod) - signs of a sudden refrigerant loss?

Sean

Good going - if you see a small oil leak at a refrigerant line fitting, indeed that's often a clue indicating a refrigerant leak.

Frosting can occur at abnormal levels if the refrigerant charge is low.

Beyond that I can but guess that there may be a control relay or board that's not working as it should.

On 2018-01-09 by Sean A.

I had a mini split installed in November, I found that after installation (week later) there was a small bit of oil on the small line set connection point. I called the tech back and he found a leak so they tightened the fitting and checked for leaks again, all seemed to be ok.

A couple weeks later the unit was frozen (i thawed it by turing it into ac mode and watched the unit steam... it got pretty hot) and after talking to the manufacturer they said is was low on refrigerant, so I had the same tech come out and recharge the system because he never recharged after the leak.

He pulled the fluid out and recharged it with the amount noted on the unit. We don't really use this unit in when its really cold outside only when the temperature is around the 32f mark.

The unit froze when it was around -3c to -5c. Previously to the unit freezing it seemed to work ok, the unit would go into a defrost mode then start heating again right away.... At least i think it was going into the defrost mode.

Now during these winter months in heating mode the unit runs anywhere from 30-60min (daytime) to 15min (evening) then defrost light comes on. The indoor unit stops blowing air, the outdoor fan shuts down, and nothing happens.

The temperature on the line sets outdoor start decreasing and the defrost cycle doesn't kick on.

An hour later you can hear a woosh noise outside and then a hum that gets louder, and the whole outdoor unit defrosts. Then the outdoor fan kicks on and the defrost light on the indoor unit goes off and the unit starts heating again for another 15min or so. The process repeats.

I'm not sure what is happening and why there is such a delay for the defrost cycle to come on

I'm concerned that the unit was ok to begin with, and having the tech pull fluid and recharge may have been a bad idea, or maybe they didn't purge all the air from the system when they initially installed the line set, or me turning the unit to ac to defrost ice buildup damaged a component. Any help or advice would be appreciated.

When they recharged the system it was -5c outside pressure was 440psi- 460 ish high side pressure was suppose to be at 550psi. When unit is in heating mode the hotter line is 37c and the cooler line is 15c, until the unit goes into defrost.
Thanks for your time

I should also add that during its operation last night, the defrost light went off and the indoor unit was heating for 10 seconds then the unit went into defrost mode again.

A wooshing noise came from the inside unit and it sounded like a crackling noise then the defrost light went off and the unit began heating again. It was like the indoor unit was going into defrost mode.
Thanks again.

On 2018-05-16 by (mod) - how to get the split system fan to turn off automatically on a Sharkair mini split

Lillian

Pretty much every air conditioner system is controlled by a thermostat that will turn off cooling when the set-temperature has been reached.

However on some units the fan will continue to run, circulating room air.

Your Sharkaire A/C unit has a Timer feature that can be set to turn the unit on and off at specific times - not quite what you seek.

[Click to enlarge any image]

The Sharkaire A/C also has a fan speed control that will manually turn the fan speed up or down or off.

The feature you want - automatically turning the fan ON or OFF - will be found in the FAN MODE feature. There you can select LOW, MEDIUM, HIGH or AUTO. Set your fan to AUTO.

Above is a snapshot of the relevant page from the Sharkaire AIR CONDITIONER MANUAL [PDF] retrieved 2018/05/16, original source: http://sharkaire.com/

If you don't have the manual for your air conditioner you can download a copy from Sharkaire or from the live link just above, or you can contact the Sharkaire company at

Sharkaire
4400-A Enterprise Place
Fremont CA, 94538
United States
Website: www.sharkaire.com
Telephone: 510-788-3707
Email: Support@sharkaire.com

On 2018-05-14 by Lillian Maynard

Hi I just had a sharkaire 12,000 btu mini split professionally installed. My question is can you set them to automatically kick off after it reaches the temperature you have set?
I thought they would kick off and on when it needs too. But mine is running all the time. Please help me.

On 2017-08-03 by (mod) - do not connect condensate drains directly to a plumbing drain

No Davis, you cannot pipe a condensate drain directly to a plumbing drain. Such a connection is unsafe because of both bacterial hazards and the chance of drawing sewer gases (explosive) into the building.

See CONDENSATE DRAINS, CODES for details

On 2017-08-03 by Davis

I have a top floor 2 room apartment in an old cooperative building where the rules currently require window units. I want to install a mini-split system with the compressor on the roof, refrigerant lines and power line running up/down through the roof along the inside of the exterior building wall to my bathroom, and serving two air handlers, one on either side of the bathroom, in the bedroom and living room.

Can I have the condensate drain pipe connect to the bathroom drains? Can the refrigerant line/power be safely installed without damaging the integrity of the roof? How would you advise the Board of my building to respond to my request for rule waivers?

On 2017-02-23 10:38:00.693492 by Anonymous

Split System A/C Doesn't heat properly. Control system turns off outside unit fan unexpectedly.

Outside unit fins get very cold, and eventually after some time (few minutes) A/C turns enters into defrost mode of operation (which is understandable).

The question is why control unit turns off outside fan? There is no problem with outside fan! It Works fine. Fan contactor also Works fine.

I also do not suspect to the control unit, since it also Works fine.

I suspect there can be two resaons for such a behaviour:

a) Malfunctioning inside the freon (since the installation guys didn't vacuum the system during instalation). They just purged the air out of the inside unit using the freon pressure from the outside unit and then quickly closing the nut). I complained, but they were persistant in persuading me that despite the precise instructions from Tosniba's Installation Manual: "Svstam must be vacuumed to (specific vacuum)..", it is not needed.

b) Temperature sensor is giving wrong dana to control unit.

A/C is branded Toshiba, RAS 13 SKHP-ES. I do not blame Toshiba at all. I think I have problem with malinstallation.

On 2016-12-17 10:48:55.112685 by Kevin k

I have a Samsung ductless ac-heat unit and want to set the heat to 50 at night and when I'm not around but it seems the lowest heat setting is 61.

I have this unit in my garage office. Should I just shut the unit off at the end of the day and turn on the next day. Or should I leave it at 61 all the time for the winter. I live in Boston area

. I don't want to tax the system by going on and off every night and morning or running it all the time. I'm not sure which is worse.

I don't want to waste my money running it all the time if it doesn't matter to the system. Thanks for advise and help. Btw. I love the system it worked great this past summer.

On 2016-09-05 17:33:59.329372 by George

Can one compressor serve 3 rooms with heat pumps?

On 2016-06-27 23:45:31.853564 by (mod) -

You will need to go to the manufacturer of your particular air conditioning unit. Given the brand model number and serial number and manufacturer can certainly provide you with the correct replacement filter screens that slide into the unit

On 2016-06-27 20:36:26.701071 by donpink@gmail.com

Where can I purchase the above mentioned filters. Mine have had it! Don P

On 2016-04-12 22:31:21.687110 by (mod) -

Kelly,

Sorry for so much aggravation, indeed often the service tech is under pressure to fill and bill rather than spend their time and your money on finding the leak.

I prefer to find the leak for many reasons.

I don't think you'd smell freon - it's odorless. Still a corroded coil is not repairable.

Possibly Carrier or your supplier can give you a price on a replacement of the cooling half of your system, but if the original equipment is old enough to be using an old refrigerant now obsolete (R22) I'd replace the system.

On 2016-04-12 18:07:41.759760 by Kelly

I have had hell from day 1 with a Carrier Mini-split 40MVQ. Installer has come out many times for freon leaks, made us pay for them to re-do THEIR installed outside valves. Finally, after 3 years (and multiple freon additions), they finally performed a leak test and found the evaporator coils on the inside unit were leaking pretty badly.

I told them that I suspected that from the beginning because every time they charged with freon, we could smell it inside the house!

Now, they are claiming that Carrier no longer carries this unit or the parts for it. It's been 4 weeks now and supposedly we are waiting for Carrier to respond to them! I know we're getting the run around. The unit is out of warranty but they should be responsible for misdiagnosing the problem.

We've already paid 61% of the original cost of the unit for new valves and freon charges!

So, my question...if there is no way they can repair this unit, how difficult is it to buy a different mini-split, either from Carrier or a different company, and install it?

IOW, will piping, wall opening size, etc need to be modified or do most mini-splits use a standard installation for these things? Can I buy a replacement and pop it in?

On 2015-12-14 10:54:22.727519 by (mod) -

Are you hearing the noise when the backup heat is on?

On 2015-12-14 01:21:30.078651 by Andrew

I have a mini split single zone heat pump/ ad in its second season of use. From day one, it has made clicking and clacking noises throughout the heating process. Sounds like expansion but it is loud and prevents a good nights sleep. I thought these things were supposed to be quite! Help!

Question: Unionaire Split air conditioner with a Honeywell type of wall digital switch compressor wiring

(Nov 20, 2012) Airkool guy said:

I am trying to replace the remote control of a Unionaire Split air conditioner with a Honeywell type of wall digital switch that controls fan speed and temperature. Iv managed to wire the fan and on off controls but I can't seem to get the compressor wiring correct. What is correct wiring procedure to follow?

Reply:

Airkool,

Over at our THERMOSTATS, HEATING / COOLING - home page there are articles on wiring details. But also for the equipment you named, most likely there are detailed wiring instructions in the box. If not give me model numbers and I'll look further.

Question: Samsung Wall Mount AC in heat mode flashes red & green & beeps: error codes mean what?

(Nov 28, 2012) Jade said:

I have a Samsung wall mount air conditioner, heating unti as well. Brand new and now when i try to put some heat on , it flashes red and green and beepes? What does this mean and how can i fix it?

Reply:

Let's get the model number; then we can find a decoding of the error codes.

Also see the Samsung manuals at SAMSUNG HVAC

Question:

(Nov 29, 2012) Mizu said:

If you run a split system just as a fan without the AC cooling, does the unit still suck air into the fan/room from outside, and is this a more economical way to ventilate a room than to use a ceiling fan (I'm thinking of cool nights, when the ambient outside air temp is lower than that inside the room)? Thanks.

Reply:

No, Mizu. The split systems discussed here do not typically obtain any outdoor air.

Question:

(Feb 18, 2013) Anonymous said:

i have a fujitsu heat pump...my outside fan will not start. error indicates fan motor error.is there a way to check this and is there a reset on the motor itself?

(Mar 12, 2013) robert said:

I have got an air conditioner labelled FIRSTLINE fsc 1200 the problem is that it is out of order, ingact when, I turn it on, 3 alerting lights all toghether remains on...what does it mean?

Reply:

Robert, if you have the owners or installation manual for your air conditioner ithat document will decode the indicator lights. Codes indicate trivial things like "clean the filter" to conditions requiring actual repair. First check the obvious things listed in the article above.

If you don't have the a/c manual, tell us the model and serial numbers and we'll see if we can find it for you.

Question:

(Mar 27, 2013) Dennis G.Gabriel said:

Why is my Samsung ductless heat pump...outside unit...freezing up?

Reply:

Dennis,

Could be low refrigerant, bad expansion valve, defective control, blocked coils. YOu need a service call by a professional.

Question:

(Feb 13, 2014) Nellie said:

Our split unit A/C works fine for half an hour. Then the outside fan picks up speed and becomes noisy. It shuts down and after several minutes starts up again, only to begin the cycle again. However at night the unit operates as it should be. It is not the compressor (replaced already).

Reply:

Nellie, it sounds as if the outside compressor/condenser unit is in trouble; I can't tell from your note if the concern is just the fan or fan motor, or if it's a more costly problem like the compressor itself.

But the fact that you say the system operates OK at night suggests that it's overheating, and having trouble working during warmer daytime hours. Some folks have tried diagnosing this overheating issue by spraying water up so that it falls as if rain onto the outside compressor condenser unit - cooling it down; in any event you need a service call.

Question:

(May 9, 2014) Rebecca said:

We own a BnB and one of our units is not working. The wall unit is lit and showing set to a/c with thermostat set on 80. The remote shows 74 and a/c. When you point the remote at the unit, it does not respond. Purchased new batteries - no change.

The two are apparently not "reading" each other. I am sold out this weekend with guests, and I don't know what to try next! I flipped breakers on and off,

I changed batteries in the remote twice. Normall there is a "beep" when the remote speaks to the unit, but there is nothing at this time. Suggestions would help - my HVAC tech is out of town on vacation!

Reply:

Rebecca, if the A/C unit is working when you control it directly from the thermostat but not from the remote unit, then clearly it's a problem with the remote-TT communication. Try powering off both units and then back on.

Question:

(May 30, 2014) monte said:

please direct me, to finding an age for Mitsubishi split system. serial #0000577t

Reply:

Sure Monte,

See the Age of Air Conditioners article at

inspectapedia.com/aircond/Data-Tag-Decoder-Air-Conditioner-Heat-Pump.php

Question:

(july 20, 2014) jesus la salle said:

I've got a code (e1) on my split air conditioner. Brand name is (comfort breeze) inverter 12000 btu. I turn it on, in the inside turns on but not the compressor. After a couple of minutes the (e1) turns on and everything turns off. What could it be?

Question:

7/31/14 Jeff said:

Our wintair split ac, seems to have trouble starting. Upon start up the outdoor unit fan runs, but for abour 10 sec.

Then a loud humm, seems to cut the power to the fan, like a relay that cant seem to engage, or a motor that wont start. This repeats for about 10 times, and only then can you hear the compressor really engage.

And then it seems fine.....for now. Any ideas.

Reply: should I hire a pro to replace an air conditioner compressor or is it DIY?

Jeff

It sounds as if the compressor is unable to start - a bad compressor motor or a failed start capacitor.

Jeff replies:

thanks for your reply, how to pinpoint the problem? I am pretty handy but dont have much experience with ac. I assume to replace any of these components, i dont need to mess with the refridgerants. Or would you recommend a pro to repair this?

Reply:

Jeff, If the compressor is failing it's not a repair a typical homeowner would nor should undertake.

Cutting, cleaning, soldering refrigerant lines, pulling a vacuum, installing new compressor, installing special burnout filter driers, and even before that, proper diagnosis of the problem are in order.

On 2017-12-14 21:52:41.705344 by (mod) -

Thank you Jack, we work hard to provide researched, unbiased, accurate information, so I am really grateful when a reader finds the site useful.

We also welcome your questions and (occasional) arguments as it's always the case that working together makes us smarter.

On 2017-12-14 20:25:32.794773 by Jack

Thanks i love this site

On 2017-12-14 01:02:52.319000 by (mod) -

Jack

It might be normal - the system may be going through a defrost cycle.

On 2017-12-13 21:23:25.541304 by Jack d

I have a 24000 BTU fujitsu halcyon dc inverter system w heat pump.
the air conditioner always works great and always worked continuously.

in the winter through out the day the unit stays on but doesn't blow air for 15-20 minute intervals.at random points in the day. is that normal behavior? or should there be a continuous flow of heat at all timese??

On 2017-10-27 13:27:22.480952 by Rob

Thank you. Do you know how low the MHK-1 temp can be set in heat mode? I looked at Amazon and could not find any specs on that.

On 2017-10-26 15:51:35.853910 by (mod) -

Rob,

I would consider installing the Wireless Remote Controller and Reciever Kit - MHK1 - but you will have some trouble finding just where to connect the control cables at your mini split to hook up the unit's receiver.

Basically you have to remove the cover, open your wall-mounted Mitsubishi mini-split, access the circuit board that controls the unit, and connect the new thermostat's receiver cable to the CN105 connector port on the control board's upper left corner. You should see the connector ID marked on the printed circuit board.

Clean Energy Wonk has an article on doing this at
https://cleanenergywonk [DOT] com/2013/04/16/adding-a-programmable-thermostat-to-mitsubishi-mr-slim-heat-pumps/

Or you might give Mitsubishi a call to ask them for other specific suggestions.

See MITSUBISHI HVAC including Split Systems at MITSUBISHI HVAC

On 2017-10-26 by Rob

I have a Mitsubishi mini-split I am using to keep a large storage room above freezing. My goal is to heat the room to 40 degrees when the outside temperature falls below that. I do not need cooling in the summer.

The wireless thermostat will not prevent setting the heat lower than 61 degrees. There is no physical reason for this limit because all it means to set the unit to a lower heating temperature is that the unit would come on less often.

Does anyone know how to bypass this artificial limit or to add a separate thermostat that will turn the unit on and off to maintain 40 degrees?

On 2017-10-10 20:55:22.047752 by (mod) -

If the unit is a heat pump that works in heating mode but not in cooling mode I suspect that a control or reversing valve is not working. Call your installer; on a brand new unit you'd hope repairs would be under warranty.

Unless like my Wappingers Falls plumber, the job was guaranteed only "until my truck reaches the end of your driveway"

On 2017-10-09 12:33:36.673895 by John

I purchased a new Klimaire dual zone mini split Heat and air unit.

It worked great for a month but now the one inside unit quit cooling. It heats fine but does not cool. The other inside unit still works great. Any Ideas?

On 2017-09-30 23:37:09.550043 by (mod) -

Light codes are going to be model dependent, so we need to know the brand and model and then find the installation and operation manual for that unit. In the back of the manual there will be a light decoding table.

On 2017-09-30 23:22:40.492720 by Bob

I've just installed a Pioneer ductless mini split unit. I have the remotes in auto settings. Over time one of the inside units will have two lights on where the temperature is displayed on the unit and not running. My question is what does this mean?

On 2017-08-29 13:45:58.204232 by Bryan

would a mitusbishi 24,000 air handler work with a mitsubishi 36,000 or 30,000 condenser?

...

Continue reading at SPLIT SYSTEM AIR CONDITIONERS & HEAT PUMPS - topic home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• DIAGNOSTIC GUIDE A/C or HEAT PUMP
• DIAGNOSTIC DETAILS A/C or HEAT PUMP
• COMPRESSOR / CONDENSER REPAIR
• MANUALS & PARTS GUIDES - HVAC - home - Master Index to All Brand Names & HVAC manuals, wiring diagrams, installation and repair guides
• SPLIT SYSTEM AIR CONDITIONERS & HEAT PUMPS
  • CONTROLS for Split System (Ductless) Air Conditioner Thermostats & Operating Controls
  • AIR FILTER MAINTENANCE for Split System Air Conditioner - How to Clean a Split System Air Conditioner Filter
  • A/C CONDENSATE DISPOSAL for Ductless or Split System Air Conditioners
  • SUPPORT SAFETY WARNING for Wall-Mounted Exterior Air Conditioner / Heat Pump Compressor/Condenser Units or Window Air Conditioner Units
  • DIAGNOSE WEAK AIR FLOW from a split system air conditioner or heat pump
  • DIAGNOSE INADEQUATE HEATING or COOLING, SPLIT SYSTEM from a split system air conditioner or heat pump
  • REMOTE CONTROL THERMOSTAT FIX or REPLACE for an air conditioners or heat pump
• SPLIT SYSTEM AC / HEAT PUMP REPAIRS

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INDEX to RELATED ARTICLES: ARTICLE INDEX to AIR CONDITIONING & HEAT PUMPS

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