Dometic duo therm fan issue

[Sharperunner]

Ive got a 97 class c with a duo therm ac unit. When I turn just the fan on my generator bogs down and dies almost immediately(fan doesnt start up). Ive replaced the start and run capacitors as well as the fan motor. Still having the same issue.

This ac unit is a bit different from my previous ones as it has two larger caps and a small PTC cera-mite. Is it worth trying to replace it or is there any other suggestions.

[JBarca]

It would help if you can provide the brand and model of the new control control board.

Are you trying to use the old Tstat with the new control board?

We need to know which Tstat, brand and model you are tying to use?

A 1997 Dometic if it is a ducted air system, with a remote T stat, it could be a bi metal T stat. Pending that t stat and vintage, there was no 12 VDC power at the control box as the older control box had an on board transformer and created its own control voltage. This could be why you have no 12 VDC at the air box area. The next generation Dometic ducted air system was what they called an analog system control board and the RV manufacture had to bring 12 VDC to the air box area to power up the control system

If you have a non ducted system, that is a mechanical control and no remote TStat.

We need more info on what you have now and trying to hook up to help better.

Hope this helps

John

[Sharperunner]

Quick update after waiting for Over a month on parts. I swapped the upper unit with an advent unit that was sold as a direct replacement. Still didn't resolve . Ordered the rest of the unit (control board and thermostat). Issue I have now is the lack of DC power near the control board. I have two wires at the thermostat providing DC but none in the direct area of the control board.

I'm not sure the control board requires DC for anything other than the thermostat. If it's solely for the thermostat I can use the existing wires. If the control board does require power Ive seen suggestions for ac/DC adapters or I could possibly just run it off of one of the lights close by. Any suggestions

[JBarca]

A 97 Dometic would be the older Brisk Air.

If your T stat has a fan "only" mode, try the fan-only option; no need to unhook wires in this case. As was said, if the fan then runs, the compressor can have issues.

If the compressor is toast, it's time for a whole new unit. The compressor gas system really is not made to be serviced unless you are a trained HVAC tech. And even then, there are gas system parts issues trying to get them.

And here is a heads-up on an entirely new unit. Dometic changed the design of the Brisk Air to the Brisk Air II. And in doing so, while the new Brisk Air II will fit in the same 14" x 14" hole in the roof, the air box in the ceiling, the control box, and the t-stat also have to be changed if you have a ducted system. If you have a non-ducted system, the air box in the ceiling still needs to be changed. They did not make the two generations of air path from the roof unit to the air box compatible.

After seeing the new Brisk Air II redesign, I am not super impressed with the longevity of the styrofoam system. I changed to the Coleman Mach brand on the last AC system I replaced. As of now, in my view, they are built better with a better warranty. You still have to change the air box and controls to convert to the Mach unit, but you are doing that on the Dometic.

Hope this helps

John

[CA_Traveler]

Remove the compressor wires and see what happens. Doug is right as you are headed towards a new unit and if it's 26 years old...:(

[dougrainer]

A Fan motor locked or has bad capacitors will NOT lug a Genset down. BUT, you have replaced those items. That should point you to another source of your problem. A Locked compressor will. I think your compressor is trying to start even tho you state fan only is selected. AND if this is the case, then you replace the complete upper AC unit. Doug

[CA_Traveler]

Pedestal is the common term for CG power mostly utility power.

[Sharperunner]

Looking in an electrical reddit forum, it seems like the ptc capacitors might be a possibility. Have it on order so I'll update on its status

[Sharperunner]

I forgot to add that it does it on our house circuit and across two different generators.

Not sure what the pedestal is

[CA_Traveler]

Does it work on the pedestal?

Did it every work on the gen?

Could be a locked rotor.

Or a gen issue.