Forum Discussion

Explorer

Aug 17, 2016

Need Help/advice or ?......

This is for all you guru's out there, and you know who you are.

We pulled our 5-wheel from Washington State to Michigan to relocate. By the way, we had no problems what-so-ever. Once we got here to Michigan, we realized our A/C wasn't working. The fan and the compressor worked, but no cold air what-so-ever.

Ordered a new A/C unit, and since it was newer then the one I had, I also ordered a new thermostat. As was stated in my research, there were no directions on installation or wiring of either unit. I was able to find a local company who sent a tech to install and wire both. The new thermostat has three "modes", fan, cool, and heat. I can set the fan speed to High, Low, or Auto while in the fan mode. The other two modes, I can set the temp. I desire.

Now, here comes my problem.

I have the fan speed set to Low, and according to the operating instructions, the fan should stay on Low with the compressor shutting off and on to regulate the temp. But, in the evening, night and morning, when the outside temp is somewhat cool, everything shuts off. Both the compressor and the fan. I must then put it in fan mode, and after running the fan for a time, I must put it back in Cool mode.

Isn't the fan supposed to run continually? Why does everything shut off? If the coils are freezing up outside, isn't the compressor supposed to shut off and leave the fan running? It is really bad at night because we can't keep the A/C running because everything shuts off.

Do I have a bad thermostat? Do I have a bad A/C unit?

That is why I am turning to all of you, for some help solving this problem.

Thanks in advance for any and all help.

NWTraveler

14 Replies

hhoffman
Explorer
Aug 17, 2016
Hello, I have fought with thermostats too. It's sounds as if the thermostat and the AC unit are not compatible. For the stage of operation when the low speed fan and compressor shut down the control signal is not present at the AC to turn that function. However the problem could be almost anywhere. Especially check with the schematic drawing and be sure that there are enough conductors between the thermostat and the AC unit. It is important to verify all connections are good. If that doesn't help find a professional.
Njmurvin
Explorer II
Aug 17, 2016
I'm no expert on RV A/C systems. But, I think you're right that the fan should stay on if set to Low or High. The only time the fan should go on/off in concert with the compressor is when it is in the AUTO position. Since the AC cools and the fan runs, I would focus on the thermostat wiring both where it connects to the AC unit and where it connects to the thermostat. Hopefully, someone took pictures of the wires connected to the old T-Stat before disconnecting. If so, maybe try putting the old T-Stat back on and see if it does the same thing.
nwtraveler
Explorer
Aug 17, 2016
That's just it. According to the operating instructions, when I set the fan on Low or High, the fan is supposed to run continually. It isn't.

And, if we leave the A/C on while we are gone, it will shut off and never come back on again, until I run the fan while in Fan Mode, then turn it back to Cool.
fj12ryder
Explorer III
Aug 17, 2016
Actually it sounds like it's working as it should.

You set the temp with the thermostat on Auto/Cool, the A/C runs to get the ambient air to that temp, it then shuts off, when the ambient air gets above the thermostat setting the A/C turns back on and the cycle repeats. Auto means the fan will run until the A/C gets the ambient air to the temp set on the thermostat, then it shuts off.