No Furnace or Heat Pump on our Dometic Duo-Therm

[3x5]

We have the Dometic Comfort Control Duo-Therm 5 button controller for our furnace, heat pump, air conditioning and fan. Suddenly it only has air conditioning and fan modes. The heater and heat pump modes are gone in both zones 1 and 2.

I took it off the wall and unplugged and replugged in the telephone plug and giggled it around, but no change.

If I have to replace the controller, is there another model or brand I can switch to? I never liked this one.

Luckily, we have a little propane heater plumbed in, so we are getting by.


Any ideas? Can anyone help us?

[Jeep401]

Originally Posted by 3x5

We have the Dometic Comfort Control Duo-Therm 5 button controller for our furnace, heat pump, air conditioning and fan. Suddenly it only has air conditioning and fan modes. The heater and heat pump modes are gone in both zones 1 and 2.

I took it off the wall and unplugged and replugged in the telephone plug and giggled it around, but no change.

If I have to replace the controller, is there another model or brand I can switch to? I never liked this one.

Luckily, we have a little propane heater plumbed in, so we are getting by.


Any ideas? Can anyone help us?

Hope you get some help on this.

My problem is very similar.
I lost only zone 2. It started out that zone 2 would disappear on the thermostat and I would turn it off and than back on again and it would come back with all functions working except there was no heat/heat pump option. I did a reset on the thermostat and now I have no zone 2 at all... I tried replacing the thermostat with no luck.
I did a lot of searching on here and didn't really come up with anything helpful.

My understanding is, to use the new style thermostat you will need to change out both boards on the units themselves.
I suspected that the thermostat wouldn't fix my problem so opted to not spend the extra money and possibly compound my problem.
Looking forward to hear if anyone else has figured this out.

[3x5]

Hi Jeep401,


I think you bought your rig about the same time we bought ours. We looked at the rig you bought in Everette WA. "Tony" was selling it. I think it was Mapleleaf RV?


Can you tell me how to reset it? I have heard about it, but haven't seen anything on how to do it yet. I guess it is pushing two buttons at once?


When you say you need to change out both boards, where are they? I don't know how all of this stuff is interconnected yet. I saw a post where the guy said a dip switch on one of the boards had slipped down from on to off probably due to rough roads. But I don't know where these boards are. Are we talking about somewhere in the air conditioners?


I did find the fuse for the furnace, and it is ok.


I would appreciate any help.

[3x5]

I recall some problem with things not showing up on the screen, and having to turn it off and back on to get them back. It may be how this started.

It is discouraging that replacing the thermostat didn't help. I was hoping that would be the problem. Can you tell me which new thermostat you are considering? I have no idea what may or may not work in there.

[3x5]

Ok. I found a March 2016 post on rvforum.net with an answer to the problem. They say there is a board in the front air conditioner with dip switches that controls this. The dip switches are vertical and can slip from on to off with rough road. I will check this, but not sure if I can for a few days. This may help someone else with the same problem:

Duo-Therm Comfort Control stopped showing Furnace Mode


Didn't expect another forum to have a better answer than IRV2!

[lazybyrd]

The dip switches are on the control board inside the unit and accessable from the roof. There is a simple process to perform from the thermostat to program the thermostat to recognize all of the components and their functions but I do not remember the process. My instructions are in my coach stored about 150 miles away. You might try to find the process on line or possibly one of the forum members who is familiar may answer.
Sorry I could not help.

[Jeep401]

I'm sure I will leave something out, but I will do my best.
First off, yes I did buy mine from Maple Grove in Everett Wa.

I bought and tried the original 5 button thermostat, less than$100, figured what the ****.

The boards are under the shrouds on the units them self's and the dip switches are on the boards.

The 120v is on the units all the time and controlled by low voltage from the thermostat to the front unit (zone 1). Which in turn then goes to the rear
(zone 2) as called for from the thermostat.

Turn the thermostat off, hold top and bottom buttons in at the same time and turn it back on,
FF should appear in the window.
Then just push the mode button and reset your desired temps and zones (if they come back).

All of my function worked on zone 2 from day one. Zone 1 on the other hand wouldn't do anything on the roof top. I spent several afternoons the roof troubleshooting.
I found the motor was stuck, which is relatively normal for units that have been sitting.
Freed it up no problem but still nothing would work, figured the motor was bad after test the capacitors.
I ran out of time to do any more before a planned trip so I put it all back together. When I got to where I was going I turned the units on and and everything worked as it should and continued to the rest of the year.
I went out to check the coach a couple of weeks ago to find the problem I described earlier.
Was working fine when parked a few week before that....

Sorry kind of a long winded response.

[Jeep401]

I found this info that might help you.
I live in the Everett area and have about a foot of snow on my roof right now so I won't get to it any time soon .

See post #9

http://www.irv2.com/forums/showthread.php?t=273145

[Gordon Dewald]

Had ours lock up and nothing worked. Turned the salesmans switches off for about a minute and the turned back on. The furnace and thermostat reset and have not had a recurrence.

[3x5]

Originally Posted by Jeep401

I'm sure I will leave something out, but I will do my best.
First off, yes I did buy mine from Maple Grove in Everett Wa.

I bought and tried the original 5 button thermostat, less than$100, figured what the ****.

The boards are under the shrouds on the units them self's and the dip switches are on the boards.

The 120v is on the units all the time and controlled by low voltage from the thermostat to the front unit (zone 1). Which in turn then goes to the rear
(zone 2) as called for from the thermostat.

Turn the thermostat off, hold top and bottom buttons in at the same time and turn it back on,
FF should appear in the window.
Then just push the mode button and reset your desired temps and zones (if they come back).

All of my function worked on zone 2 from day one. Zone 1 on the other hand wouldn't do anything on the roof top. I spent several afternoons the roof troubleshooting.
I found the motor was stuck, which is relatively normal for units that have been sitting.
Freed it up no problem but still nothing would work, figured the motor was bad after test the capacitors.
I ran out of time to do any more before a planned trip so I put it all back together. When I got to where I was going I turned the units on and and everything worked as it should and continued to the rest of the year.
I went out to check the coach a couple of weeks ago to find the problem I described earlier.
Was working fine when parked a few week before that....

Sorry kind of a long winded response.

Good info. I tired the Reset. I got the FF. When I released the Mode and Zone buttons they changed to EE. Did it several more times. Turned if off and unplugged for long time. Still have nothing but EE on my screen.

I have a couple of other projects going, so I may have to put this off for a while.

Anyone know what EE means?

[Schuby]

I had a similar problem with mine, turned out to be the solenoid or reversing value. Had them replaced and worked fine.

[Jeep401]

EE is an error I believe,
I got that once when I unplugged the thermostat w/o turning off by mistake.

[sandy1]

You may have lost comminuation between units and thermostat. There is a phone style cable from thermostat to front ac control board then from front ac to rear ac controls board and on 2004 and later from rear ac to pre wire for hydro hot. There are two inline phone connectors above inside the interior filter assembly. They can loose contact with a little condensation. You can unplug and plug the connectors and that may reestablish connection. Also the end for hydro hot if not used may contact something and short out causing a communication problem.

[Jeep401]

Thanks for the suggestion, I will look at that too.