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 > How to fix Dometic Comfort Control thermostat problems

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CR3999

Katy tx

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Posted: 07/10/16 06:59pm Link  |  Quote  |  Print  |  Notify Moderator

Doug, when I press the inside temp button it is reading " -5 ". And the AC does not cut off. This is on zone one. I get up in the morning and it is a bit nippy.
Zone two works just fine.
What do ya think is causing this problem? I was going to buy a new thermostat and saw this thread, so I thought I'd give it a shot.
Thanks, Darrell

Pete_k

Stantonville Tn

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Posted: 09/24/16 12:28pm Link  |  Quote  |  Print  |  Notify Moderator

Anyone had an issue where the Thermostat will not even light up? Ours did this last year. I messed with it and got it back working. Now this year nothing on the panel lights up. Just like its dead?
Pete


2022 Ram Big Horn DRW on order">
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drusher

Saint Louis

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Posted: 09/24/16 01:47pm Link  |  Quote  |  Print  |  Notify Moderator

The power switch on bottom of the older dometic thermostats had no physical support. The solder joint can easily crack with normal use of the power switch. In the early stages, your AC will turn on and off while you are going down the road and might not turn on at all depending on what you had for lunch (hee hee). It gets worse with time as the cracked solder gets junk and pollutants in the crack and then it wont work at all.

Take the board out of the case and resolder the power switch. Be sure to use electronic solder, not plumbing solder.

Check the circuit traces where the switch is mounted to make sure they are not cracked. If the trace is broken, you can scrape the green insulation off the trace carefully with a small razor knife. Use a short piece of wire cut off a resistor to bridge the break and make it stronger too. Cut the piece of wire too long and bend the end up so you can hold the wire in place with small needlenose pliers while soldering, then cut the end off with a little wire wire cutter.

On mine I resoldered all the joints because there were a lot of cold solder joints (which crack easily). You can tell a cold joint because it is not shiny. Do this carefully with a fine tipped iron, and inspect it to make sure you did not make any solder bridges.

After soldering, clean rosin off the back of the board with a clean toothbrush dipped in rubbing alcohol. You do not want the impurities and chemicals in the rosin to attack the solder joint later.

Pete_k

Stantonville Tn

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Posted: 10/09/16 10:31am Link  |  Quote  |  Print  |  Notify Moderator

Found the issue with ours. Still not sure what to do for the fix. But found the issue. Went to unplug the phone plug from the back of the controller. AS I started to unplug it. The Controller lights came on. Pushed the plug back in all the way. Lights go's out, back it out some. Works again, so now to figure out if its the plug male or female end?
Pete

rgatijnet1

Florida

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Posted: 10/09/16 11:03am Link  |  Quote  |  Print  |  Notify Moderator

On my Monaco coach, they installed the Dometic CC thermostat on the exterior wall. This caused all kinds of problems with maintaining a comfortable temperature inside the coach, depending on if the exterior wall was in the sun or in the shade. I removed the thermostat, placed a 1" piece of styrofoam behind it and installed it spaced out from the wall that 1". It now does a much better job of maintaining a comfortable temp in the coach.

dougrainer

Carrolton, Texas

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Posted: 10/09/16 12:54pm Link  |  Quote  |  Print  |  Notify Moderator

rgatijnet1 wrote:

On my Monaco coach, they installed the Dometic CC thermostat on the exterior wall. This caused all kinds of problems with maintaining a comfortable temperature inside the coach, depending on if the exterior wall was in the sun or in the shade. I removed the thermostat, placed a 1" piece of styrofoam behind it and installed it spaced out from the wall that 1". It now does a much better job of maintaining a comfortable temp in the coach.


You can buy the remote Thermister for the front Zone 1 and when that is connected to the Zone 1 AC board will remove the Wall CCC from being the temp selector. Just route the temp bulb out the ceiling of the unit about 1 foot from the intake filter of the Zone 1 AC unit. Doug

rgatijnet1

Florida

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Posted: 10/09/16 01:55pm Link  |  Quote  |  Print  |  Notify Moderator

dougrainer wrote:

rgatijnet1 wrote:

On my Monaco coach, they installed the Dometic CC thermostat on the exterior wall. This caused all kinds of problems with maintaining a comfortable temperature inside the coach, depending on if the exterior wall was in the sun or in the shade. I removed the thermostat, placed a 1" piece of styrofoam behind it and installed it spaced out from the wall that 1". It now does a much better job of maintaining a comfortable temp in the coach.


You can buy the remote Thermister for the front Zone 1 and when that is connected to the Zone 1 AC board will remove the Wall CCC from being the temp selector. Just route the temp bulb out the ceiling of the unit about 1 foot from the intake filter of the Zone 1 AC unit. Doug


Thanks, that makes sense on a location for a remote sensor.

MagicMikeD

Indiana

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Posted: 11/07/16 01:53pm Link  |  Quote  |  Print  |  Notify Moderator

I have the 5 button and it all of a sudden just flashes Zone 3.

I can turn it off and on about 6 or 7 times, and every mode shows up except furnace. The A/C or fan doesn't kick on. Then after a minute or so, it will go back to blank except Zone 3.

Any ideas? Tstat? Board?

Megmcc08

Louisiana

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Posted: 08/19/17 09:23am Link  |  Quote  |  Print  |  Notify Moderator

The a/c wont come on. It's a domestic dual thermostat. The 10 button. We tried switching with new thermostat. We flipped breakers in/outside. I looked at the circuit boards and don't see any burned wires. We just had the whole unit replaced in both a/c. I am not sure if it's a voltage problem. I get nothing on thermostat so it's incredibly hard for me to diagnose issue. Any help greatly appreciated. 5th wheel crusader 2014.

hostage

North america

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Posted: 08/19/17 09:48am Link  |  Quote  |  Print  |  Notify Moderator

Megmcc08 wrote:

The a/c wont come on. It's a domestic dual thermostat. The 10 button. We tried switching with new thermostat. We flipped breakers in/outside. I looked at the circuit boards and don't see any burned wires. We just had the whole unit replaced in both a/c. I am not sure if it's a voltage problem. I get nothing on thermostat so it's incredibly hard for me to diagnose issue. Any help greatly appreciated. 5th wheel crusader 2014.


whats weird to me is if you have two roof AC systems and one thermostat
which is pretty much the norm these days there still has to be two communication wires going to each Unit; the chances of both failing at the same time is confusing for sure;; how long after replacing both units did the problem start? Did both stop operating at the same time?
looking for a common denominator here may help
Will the thermostat run the furnace systems?

* This post was edited 08/19/17 10:05am by hostage *

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