AC compressor runs continuosly Fixed!

[techwrench]

This problem seemed to be intermittent at first, now it is constant. AC compressor does not shut off regardless of Dometic Duo Therm thermostat setting. Have to shut off the breaker. Seems to cool or heat and work fine otherwise.

 

[danemayer]

Re: AC compressor runs continuosly

Hi techwrench,

If the FAN setting on the thermostat is set to HIGH or LOW, the overhead fan runs continuously when the thermostat is set to either HEAT or COOL. Change the setting to AUTO.

 

[cookie]

Re: AC compressor runs continuosly

Hello Techwrench and welcome to the forum.
I have a couple of quick thoughts here.
Do you have a digital thermostat?
If you do, scroll through the thermostat menu and look for the fan setting.
Be sure it is set to 'Auto' not 'High' or 'low'.

Peace
Dave

 

[techwrench]

Re: AC compressor runs continuosly

Thanks for the replies. It's an analog thermostat. Compressor runs regardless of fan setting. Compressor only stops if I shut off breaker.

 

[danemayer]

Re: AC compressor runs continuosly

Thanks for the replies. It's an analog thermostat. Compressor runs regardless of fan setting. Compressor only stops if I shut off breaker.

So in addition to the temperature setting lever, the thermostat must have a switch that offers a choice of HEAT or COOL. Assume it's on HEAT. Is there another switch for FAN speed?

Pictures of the Duo Therm Analog thermostat show a switch for FAN that can be set to ON or AUTO. Is that what you have and have you switched it to AUTO?

 

[techwrench]

Re: AC compressor runs continuosly

There is a switch for heat, cool or off. Fan switch is Hi/Lo and Auto/On. Compressor continues to run regardless of switch position.

 

[danemayer]

Re: AC compressor runs continuosly

I'd open the thermostat and see if any of the wires are loose or shorted or broken. If all looks ok, you may have a problem in the A/C relay box which is usually located in the ceiling above the air return for the A/C.

 

[Rickhansen]

Re: AC compressor runs continuosly

I'm guessing the compressor start relay contacts are welded closed. A good rap with the handle of a screwdriver might free them, but you should replace the relay if that is indeed the cause.

 

[heartshot]

Re: AC compressor runs continuosly

My AC unit ..... 2010 Sundance......is doing the exact same thing.
I have not figured it out yet.
Been using the breaker to shut it off.

 

[techwrench]

Re: AC compressor runs continuosly

I forgot about this post. Thanks for helpful replies. It was the thermostat. Had it replaced with a Dometic and it works fine. Thanks again for the help.