Coleman mach ac units

[Kelliegirl2u]

We recently purchased a new (to us) 5th wheel that has 2 ac units. The thermostat on the wall is blank, does not appear to have any power to it. We have taken the ceiling plenum off and looked for the green LED light mentioned in different forums. We see the light but it is not on.
We have checked all fuses and circuit breakers and everything appears to be working. We have purchased and installed 2 new batteries.
Of course since the thermostat is blank, we can’t check the furnace either.
Anyone have any ideas where to start?

[BFlinn181]

The thermostat should be powered by the 12v batteries. Check all fuses or circuit breakers that might power it. Then take the thermostat cover off and check for 12v there and also the ground connection. Using a couple of jumper wires from a known good 12v source you could try connecting the thermostat directly to check it's function and ability to run the A/C and furnace.

You might also do a Google search for the make and model of thermostat you have, look for an owner's or service manual to troubleshoot the thermostat.

[DancinCampers]

There may be a fuse on the tsat board.