5 button thermostat

[Chuck B]

I have an 06 montana 2980RL That worked fine untill I brought it home from our campsight. I had a burning smell arond the roof A/C unit and no power to the 5 button thermostat. I found a burnt out circut board inside the A/C and replaced it, I also found the phone type wire cut through, So I spliced it back together. I tried to turn the heater on and at first the display came on normally but the heater didn't come on. I did the reset and got the FF but as soon as I let go of the Mode and Zone buttons it goes right to EE. I tried several times and it keeps going right back to EE. Any suggestions?
Chuck Bergeron
Rochester, Wa.

[ChuckS]

The "EE" error is telling you that you have a communication error between that thermostat and the Roof AC control board.

You already stated you found the RJ11 line cut and spliced it..

Use multimeter and ohm out the RJ11 cable from end to end and you will find that you have a break in one of the two CANBUS lines...

Red and Black are 12 vdc power and ground.. Yellow and Green are the two CANBUS wires...

NOTE - if you have TWO AC units then there is an interconnect RJ11 cable from Zone 1 to Zone 2 control boards...

** If there is an issue with the second AC control board OR the RJ11 cable the thermostat will also display the "EE" that you are seeing

[ChuckS]

IF you have troubles trying to verify the RJ11 cable from thermostat to Roof Zone 1 and Zone 2 control boards you can always go buy a length of 4 wire phone cable an d some RJ11 connectors

Then make up a "Test" harness long enough to reach from Roof AC control box down to thermostat

To TS go up and remove the RJ11 cable that runs to second AC unit and leave disconmected

Now Do a RESET on the thermostat and see if it now has good display with NO EE error displayed

If good then you know issue is with either the interconnect cable to the other AC or a bad control box on second AC

If you dont have Two AC units then build that 4 wire telephone cable and wire up the RJ11 connections per the manual ( they are not wired like standard phone cable )

Now use that cable and plug it into roof AC unit and hang it down to thermostat and plug in and RESET thermostat

If error is gone then you know you have issues in the RJ11 cable

[Chuck B]

Thanks Chuck! I have a long section of phone wire, How would I change the wiwes to make that work? I don't have a manual. I really appreacate your help.
Chuck

[ChuckS]

Not sure of the exact thermostat you have in your 2006.. but this is the wiring config for the four wire telephone cable used on “some” Dometic AC control boards to thermostat ..if your thermostat has just a telephone plug going to it ..

If it is hard wired then the wiring of course is different then what I have told you

See images for RJ11 plug wiring

[Chuck B]

I pulled the cable out as far as I could and found another break in the black wire. I cut out about a two foot section and spliced it together and now everything works. Thanks again for your help.
Chuck B.

[ChuckS]

Originally Posted by Chuck B

I pulled the cable out as far as I could and found another break in the black wire. I cut out about a two foot section and spliced it together and now everything works. Thanks again for your help.
Chuck B.

Glad you found the second break in the wire.. I would suspect father time may have caught up with that cable with the second break in it.. If the issue returns you probably will need to string a new phone cable