Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 10, 2025 ...

Dometic thermostat

December 26, 2015, 05:59:27 pm

 Now that I was able to drive the FT and get fuel I am able to use the Aqua Hot and generator. Which brings me to a new problem with the Dometic thermostat. The thermostat pictured came on the FT when I bought it. searching the archives I found about changing to a 5 button from the original 4 button but nothing about the one I have the problem is that when zone 1 is set for furnace the front air conditioner comes on if I am on generator or hooked up to power. The rear air conditioner does not come on when zone 2 is set for furnace and is working fine. The zone 1 is heating with the Aqua-Hot at the same time as the air comes on. If I unplug or turn off the generator just the heat comes through on zone 1 I will call Dometic on Monday but if someone has had this problem before pleas let me know. From Barry's info on a 5 button it could be that when they upgraded the thermostat and change the boards in the air conditioners the wrong dip pins were set.
The first owner of my coach was meticulous and saved all records and manuals up until he sold it in 2005 since then nothing is in the folders It has a residential refrigerator with a 2012 manufacturing date no record or manual 2 flat screen TV's no record and this thermostat no manual or record. So I am starting fresh with all my repairs and upgrades and will keep records.

Quote Selected

Re: Dometic thermostat

Reply #1 – December 26, 2015, 08:20:00 pm

I don't have Aquahot but I am familiar with that thermostat and its installation when I changed my system over to it so it may be of use to you.

My system required new circuit boards to replace the old circuit boards in the rooftop units.  On the circuit boards are a series of dip switches that need to be set to the correct setting for what you are trying to do with it.  In my case, my RV has one furnace so the the dip switch on the front AC unit circuit board was designated as the master unit and set to only allow either the front AC, heat strip, or furnace to run but not either of the other systems at the same time.  The rear unit was set up as the slave unit and can run the heat strip or AC while the front unit is running the furnace.

It sounds like whoever installed the unit did not put the dip switches in the correct positions on the front unit and you'll have to do a bit of digging to find out what those settings are.

Edit:  page 15 of this installation manual should tell you how they need to be set.

http://www2.dometic.com/b3056cd0-1a5b-4a15-8c1f-1d322d4ac84d.fodoc

It could also be a simpler fix than that too.  If your fan setting on Zone 1 is not set to auto while on furnace, the rooftop fan is the one that will be the one spinning.  Check to make sure that FAN is set to AUTO on Zone 1.

Quote Selected

Re: Dometic thermostat

Reply #2 – December 26, 2015, 10:37:19 pm

Thank you

That was the problem zone 1 was on high. All is working now. I will download the instructions so I will know how to use the thermostat.

Quote Selected