AC in 2012 Big Country (Living room) has no power to thermostat.

[icechex]

Thermostat is completely dead. No power to it. I've checked the breakers/fuses and they all show to be good. Wondering if there is a fuse/breaker on the roof? Also, could someone tell me what is the voltage to the thermostat.

 

[danemayer]

If a Dometic Single Zone LCD thermostat, I think it might be 5V DC. On a 2012, if this is for the living area A/C, I'd expect the thermostat wire to connect to a gray relay box just above the air return. I believe the power to that box starts at the main fuse box.

If checking fuses by looking for an illuminated LED in the fuse panel, that may be insufficient as the LEDs only illuminate when 1) the fuse is blown, AND 2) there's a load on the circuit. You may need to visually examine each fuse, and perhaps even check with the ohm function on a volt meter.

 

[wdk450]

These older Doemtic thermostats are wired a little backwards to what you are used to. With all wires from the Air Conditioner control box disconnected from the thermostat, measuring to a true 12vdc chassis ground, the white wire will be 0 volts DC (12 VDC ground). The other wires from the Air conditioning/heater control box in the AC unit should all read +12 volts DC to ground. The thermostat switches completes a circuit to ground from the AC control board when they close. If you have no +12VDC to ground on any of the thermostat wires, you need to check the +12 VDC coming into the AC control box from the 12 VDC fusepanel. Be aware that the LED indicating 12 VDC fuses may not glow when blown if there is a small or no electrical load on the fuse circuit. The load completes the circuit for the indicator LED. An unblown fuse is wired to short current around the LED, and the LED won't light under non-fuse blown conditions.

 

[icechex]

If a Dometic Single Zone LCD thermostat, I think it might be 5V DC. On a 2012, if this is for the living area A/C, I'd expect the thermostat wire to connect to a gray relay box just above the air return. I believe the power to that box starts at the main fuse box.

If checking fuses by looking for an illuminated LED in the fuse panel, that may be insufficient as the LEDs only illuminate when 1) the fuse is blown, AND 2) there's a load on the circuit. You may need to visually examine each fuse, and perhaps even check with the ohm function on a volt meter.

thanks so much for the reply

 

[icechex]

These older Doemtic thermostats are wired a little backwards to what you are used to. With all wires from the Air Conditioner control box disconnected from the thermostat, measuring to a true 12vdc chassis ground, the white wire will be 0 volts DC (12 VDC ground). The other wires from the Air conditioning/heater control box in the AC unit should all read +12 volts DC to ground. The thermostat switches completes a circuit to ground from the AC control board when they close. If you have no +12VDC to ground on any of the thermostat wires, you need to check the +12 VDC coming into the AC control box from the 12 VDC fusepanel. Be aware that the LED indicating 12 VDC fuses may not glow when blown if there is a small or no electrical load on the fuse circuit. The load completes the circuit for the indicator LED. An unblown fuse is wired to short current around the LED, and the LED won't light under non-fuse blown conditions.

thanks for the informative reply ....