Just last month, I did a Dometic analog to digital thermostat replacement and want to share with you (images included) step by step how you too can replace Domestic analog thermostat with digital one.
I have divided the instructions into two parts and the bottom of each part has images that will better guide you. Cheers!
How to Replace Dometic Analog Thermostat with Digital
- Turn off the main breaker disconnect the battery to cut all power to the AC unit.
Note: There should be a 12-volt supply to the control box, so ensure you kill the power before moving to the next step.
In my case, the digital control box wa smaller than the analog box (pictures in the later part of the post). But, they both stay in the same brackets.
- Now, cut the tstat wires (GET PLIER ON AMAZON), heater wires and 12-volt wires.
- Unplug the AC control wire bundle, freeze sensor, and disconnect the 110-volt supply.
- Remove analog control box.
- Then remove the old freeze sensor and replace with the newly acquired sensor
- Press new sensor into fins one inch from bottom and gently bend fins around sensor to hold into place. Again, pictures shared after this section of the post.
- Connect the 110-volt supply to the digital box, then match the wire colors using wire nuts.
- Locate the dual heater wires and attach the supplied spade terminals. The heater wire in my RV is a dual wire cable made up of a white and red wire.
- Affix the digital box to the bracket on the AC unit with supplied screws.
- Plug in the AC control wire bundle
- Plug in the heater wires
- Plug in freeze sensor.
- Remove analog tstat
- The digital tstat only uses three of the seven wires of the tstat cable. I picked orange, red, and white, to match the color wire at the control box.
- Connect the three wires.
Orange: Common or communication
Red: 12 volt positive +
White: 12 volt negative –
Before you attach Tstat to the wall, ensure you cover the hole in the wall where the Tstat cable protrudes. That will prevent hot air from escaping wall cavity and then giving a wrong reading to the Tstat. In my case, I used some insulation and covered with foil tape.
- Look into the control box
- There should be a wire harness that includes – black, red/white, and orange.
- At the control box there is a wire harness that consist of a orange, red, red/white, and black.
Orange wire harness to orange tstat wire.
Red harness wire to RV 12-volt positive (+) supply
Red/white harness wire to tstat red (+) wire
Black harness wire to RV 12-volt negative (-) supply AND white (-) tstat wire
- Then Plug wire harness into the control module.
Looking from left to right…
110v supply…freeze sensor…tstat wire harness….heater wires
- Wire tie wires into a bundle and zip tie.
- Turn on the breaker and battery disconnect and test AC.
Congrats! That should do it!