[Wanderman]

OK so the Front AC saga continues. Today I got underneath and tested the board and components. The board is bad. Removed and examined...the traces are cooked. I will rework that for a spare. Swapped in a known working board, and two new capacitors. Immediately I can turn on the FAN (AUTO/FAN switch to ON) and it works! I can also vary the speed with the HI/LO Fan switch.

Now the odd news. Setting FAN to AUTO and either speed, moving the main switch to COOL and making sure the thermostat is set many degrees cooler than the displayed room temp...does NOTHING. No fan, no compressor, nada.

With Richard's excellent instructions I tested the thermostat by bypassing various functions and testing the compressor by jumping 12V power (RED) to the YELLOW (Y1) wire. Immediately the compressor fires up and with the fan in the ON position I get great cooling...the AC works!

This is a brand new RV Coleman mach two stage thermostat sold to me by NEWELL as a direct replacement. I have the same on on the rear Dual Compressor SCS2702.

I checked and rechecked the wiring as the colors change between the SCS harness and the thermostat.

Only thing I can think of at this point is Newell sold me a bad thermostat(?)

Any other ideas before I call and complain