Roof air conditioner has error message

[exportman]

I have 2 roof ACs. One works but when I switch to another zone to get the rear AC to go on I get a "ER" message on the thermostat box and it won't turn on. The manual says I should take it to a dealer. Just wondering before I do that if there is anything I can check out myself. Thanks.

[exportman]

We have misplaced a hand held remote. Would the missing remote be causing a problem or do you think that the wall mounted thermostat overrides the remote?

[Chris_Bryant]

Sorry for the delay- I was hoping Doug would jump in, as I don't deal with Coleman/RVP very much. What little info I have points to a bad room temperature sensor, but I don't have any specs on what the resistance should be. It will be connected to the unit giving the Er message- I would start by measuring the resistance anyway- could be simply a bad splice in the wires.

[exportman]

Thanks for asking for more info, Chris. Anything mor that you need?

[exportman]

Roof airs are RV Products a division of Airxcel 8000 series
The thermostat is RV Comfort ZC for 8330A335

[Chris_Bryant]

We need to know the make and model of the air conditioners, and which thermostat(s) they use.