Roof AC - Compressor on, fan is not

When mine did that, no fan but compressor on, it was a bad control board in the unit. Dealer replaced it under warranty.

dlplaia wrote:
We have a brand new Dometic AC, replaced because of the same problem (see below) plus non-cold air.

The AC is in Colorado 5th wheel; wall thermostat with remote; ducted in ceiling. When we turn the AC on, the compressor comes on but the fan doesn't. We've tried every setting with fan speeds, temps, etc. Every once in a while we can finally get it working together.

We figure the problem to either be in the controller box (that the AC plugs into) or the thermostat.

We'd love to hear input from you knowledgeable RV folks!

Thanks!
Debbie

Is there a way to "reset" the thermostat? There's a chance the thermostat may use some kind of firmware that may have become corrupted. A reset or reload may clear the problem---much like rebooting your phone or computer.

dlplaia wrote:
Doug, every once in a while we could finally get the fan going after trying different approaches for an hour. (desperation when it was too hot outside) Still, something is not right and we don't want to risk blowing the seals on the new AC trying to get things to run right.

The wall thermostat is a Dometic Remote Comfort Control.

Sorry, I have never seen this remote system and very few OEM's use this remote system. That means the upper control package is something I am not familiar with. Doug

Doug, every once in a while we could finally get the fan going after trying different approaches for an hour. (desperation when it was too hot outside) Still, something is not right and we don't want to risk blowing the seals on the new AC trying to get things to run right.

The wall thermostat is a Dometic Remote Comfort Control.

dlplaia wrote:
Nope, the fan did not come on in fan only mode.

Well then there are 3 possible causes:

Bad stat
Bad wiring
Bad fan

You need to know a little bit about exactly how things work in order to be able to do a couple of simple tests to see where the problem IS. Someone here can, no doubt, help with that. That is not me.

If you replaced the entire air handler including the fan, then that pretty much eliminates a bad fan. Might not eliminate a power problem going to it though.

So, you state that the OLD AC and the NEW AC, the fan has a problem? You stated the OLD AC did not blow cold air. IF the fan did not run, how did you know you did not have cold air?????? But, since the unit is NEW, and you state you still have a non functioning FAN, The ONLY thing it can be is either the Control Circuit board or the connections to that 6 pin multiplug on that control board. It could be the wall tstat, but it depends on what MODEL of Dometic Tstat you have. Also, do you HAVE a Dometic wall tstat or have you or someone else installed a residential type tstat? Doug

capacitor??

I would be interested in this as well. I am having the same problem.

Moved from technology

Nope, the fan did not come on in fan only mode.