Plus AND Minus 12v from AC to Thermostat
I have a Dometic A/C and a Dometic single zone thermostat. The thermostat requires plus AND minus 12 volts. The schematic of the A/C control box indicates that the plus AND minus 12v come from the pow...
Forum Discussion
The DC power and GROUND to your thermostat on this Dometic are supplied from 12 volts DC that is coming from the battery to the air conditioner control module.
If there is no 12 volts at the controller then the thermostat will be dead and the ECM for the air conditioner will not work.
Power is supplied in this setup from air conditioner control module to thermostat across a 4 wire phone cable .... however it is not wired at the RJ45 plug like a standard telephone cable.
The other two leads on the phone cable are for CANBUS communication back and forth from the thermostat to the controller.
Additionally most Dometic units also have the furnace being communicated with across this same telephone line and there will be a separate lead from Zone 1 air conditioner control module running down to the furnace control board.
If there is no 12 volts at the controller then the thermostat will be dead and the ECM for the air conditioner will not work.
Power is supplied in this setup from air conditioner control module to thermostat across a 4 wire phone cable .... however it is not wired at the RJ45 plug like a standard telephone cable.
The other two leads on the phone cable are for CANBUS communication back and forth from the thermostat to the controller.
Additionally most Dometic units also have the furnace being communicated with across this same telephone line and there will be a separate lead from Zone 1 air conditioner control module running down to the furnace control board.
