What Other Color Would the 12v Power Wire Be on the Replacement Thermostat for Dometic AC?

Updated 05/28/2025 | Published 05/24/2025

Question:

what other wire other then the black in wiring a three wire thermostat when you dont have a black wire.

asked by: Leo A

Expert Reply:

The Replacement Single Zone Thermostat for Dometic RV Air Conditioners item # DMC79FR has 3 wires. A black, orange, and red. I wouldn't know what other color wire would be used. Here are the wires individual functions though so you can trace them back to their source and identify them that way.

The black wire is a 12v supply power wire.

The red wire is the 12v from control box to thermostat.

The orange wire is the from supply to the control box.

expert reply by: Jerred H

Replacement Single Zone Thermostat for Dometic RV Air Conditioners
(click to enlarge)

Leo A.

5/28/2025

Thanks I think I might have solved the problem in looking at the wire connections over head next to the a c unit the blue wire wasn't connected to anything. Made the connection with the black problem solved. Thank you. Leo