Originally Posted by RichHog
Furnace stopped working on a trip back in January. This is the standard AC (duo therm/ Penguin I think ) Airstream put in most trailers for many years. Just had the trailer in for repairs at a great shop and was told that a circuit board in the topside unit is bad that lets the thermostat (lcd type in the bedroom) control the furnace. AC unit works, heat pump , fan work. And they said that when they short two wires together in the overhead unit the furnace fires up and works fine.
Evidently the main AC units are now discontinued and buying a replacement board isn't an option. Not available. Options are to replace the AC unit itself $$$, or for about $500 they could pull a new set of wires and put a thermostat somewhere for furnace only operation. Oh another option is to cut the two wires in the overhead unit and put an on/ off switch on the side of it.
So I'm reaching or here as I'm sure here is a board out there some where to replace this or a solution that is practical. I believe the unit is an 11,500 btu unit.
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First, as of last year, Dometic still had replacement boards in stock for the now discontinued CCC-I 5-button thermostat. Also, have the tech tried to toggle the furnace 'DIP' switch a few times? It might simply not be recognizing the presence of the furnace.
I also don't agree with the conclusion from the shop's diagnosis, not the diagnosis itself. I believe that if you are willing to replace your thermostat with a new CCC-II unit, you can retro-fit the corresponding new board to your older A/C unit, assuming that they have checked with Dometic and are certain that there are no more replacement boards for the CCC-I available.
That would allow for the same wiring to be used thru-out by replacing the upper relay board and the wall t/stat. Your furnace will still operate on the new t/stat, along with your A/C unit.
I've done several of these 'upgrades' to older A/C units in the past, replacing the older 5-button CCC-I with the new CCC-II along with the corresponding control board for folks that wanted the newer technology.
If I was back in FL, I'm sure that I have your exact board laying around in my shop. Unfortunately, I won't be back there until Nov. 1.
Best to call Dometic's hotline with your model#, serial# and product number from your A/C unit and check the backward upgrade possibilities as I outlined above. There is also a remote chance that you can use their 'single zone thermostat' kit as well.