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Arctic King MWK-25CRN1-MI4 Compressor Not Shutting Off


Jun 22, 2017
Los Angeles
Model Number
1-5 years
Arctic King MWK-25CRN1-MI4
Installed through the wall
Two Years Old

A week ago (06/15) I noticed after about ten minutes that the compressor did not turn off. I took the front grill and filter off, and noticed that the fins on the evaporator coil were frosted white. I tried turning the thermostat up to 76 degrees, the compressor kept running. I tried turning it to fan only, the compressor kept running, and the display showed 55 degrees. I tried turning off the a/c, the fan turned off, the compressor kept running. I pressed the reset button on the plug-in, the fan stayed off but the compressor started running again. I eventually unplugged the a/c and let it defrost for about eight hours. It has been running correctly ever since then.

I had a repairman come in last Monday (06/19). He turned the temperature down to 69 degrees, and when the compressor did not kick on he said it was the compressor, and set it back to 74 degrees. About five minutes later, I turned it back down to 69 degrees and the compressor came on. He still said it was the compressor. I am probably wrong, but I seem to remember hearing that there is a safety waiting period between when the compressor last shut off and when it will start again, and I wonder if that was why it worked the second time.

Filter is kept clean.

My questions are:

1. Is it likely the compressor given the above?
2. Is it likely the control panel?
3. Is there some other probable cause?
4. Are there other tests the repairman should have done?

And then some questions about running the a/c unit:

1. Is it a problem running the fan 24/7 to keep the air moving, with the a/c thermostat set 74 degrees, as long as the cooling environment indoors and outside is within specifications in the manual?
2. My apartment manager says that running the fan all the time will heat up the unit and cause the compressor to stay on, is that correct?

I am not a very technically savvy person, and I am trying to figure out what to do next. I have some indoor pets that would be in bad shape if the a/c failed while I was away all day. If the apartment owner is not willing to fix or replace the unit, I will probably have to buy a portable unit as a backup if the main a/c fails.

Thanks for any help. Sorry for the long post.

There's probably nothing wrong with the machine. The frost problem happens when the outside temperatures start getting close to triple digits. The condensor has a hard time getting rid of the heat so saturated gas is boiling off causing the frost. As a rule of thumb whenever the outside temp climb above 100*F any setting below 75*F will usually cause the evaporator to frost up. As far as the compressor continuing to run can be a sticky relay caused by the heat. What size room are you trying to cool? The best thing you can do is slide the AC unit out of the case, take it outside and use a hose to clean out the condensor. The only thing you need to watch is getting water on the control board so protect it with some plastic. Anywhere else is fine as long as you let it sit in the sun and completely dry. Spray the fan motor and electrical connections on the compressor and capacitors with WD40
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