Originally Posted by 2dogtraveler
Saw a post recently regarding an add-on thermostat to AC unit. Now can't find it! We have Coleman AC; fan runs continuously. Want to add a thermostat to turn fan off when compressor is not running. Any ideas will be appreciated.
You may have seen my article in Airstream Life regarding using an extra thermostat to simultaneously run the heat pump and the furnace.
I don't think a second thermostat is the answer to your problem. The fan should either run continuously or run only when the compressor is running. I don't know how you could accurately synchronize a second thermostat to insure the latter condition. You definitely do not want the compressor running with no fan running.
A relay could be used to run the fan whenever the compressor runs. This is essentially how the Dometic in my Classic works although the relay is part of an electronic board in the Dometic and synchronization is insured.