Dometic Air Conditioner will not cycle

[solutionsville]

I have a 2019 Cardinal Luxury and it has a 15K BTU AC in the rear. I have been living full time in it and ran the AC mostly from Mid April thru late August without issue. At some point it stopped cycling on and off when it reached the set temp of 70 degrees. As I am living in it I it is not feasible to leave at the dealer for 2-5 weeks or more while waiting on Warranty repair.

So, Up I climb and pop the top. I find the Motor Start Capacitor was failed. I replace it, and have the other Capacitor tested as well and it showed it was good. Button it all up and it runs fine for about three weeks. Same problem, it stops cycling. I go up again and find the Motor Start Capacitor has failed again, so I decided to change it and the Relay Control board. Same thing, it runs about 2-3 weeks and it failed again.

I called Dometic support and they said it would be one of three things. Thermostat, Relay Board, or the wiring between the two. They suggested hooking the thermostat up on the roof and see if it cycles correctly. Continuity checks on the wiring indicates no loss there and no work had been done that would have nicked or dinged the wiring. So I replaced the Thermostat as well.

Hooking the Thermostat at the AC worked for the time I had it there. Every time you reset the AC by shutting the breaker off and then turning the thermostat to desired value it worked normally for the day. Extended periods it would go back to not cycling. I have not going back up there today yet, however I suspect that the Relay board again and the Capacitor will need to be changed out again. I think I will change both the Motor Start and Run capacitors this time.

So, all that said, does anyone have any better suggestions as to what to change or look at next?

Thank you in advanced

[Chris Pastuzyn]

Typically if that unit is eating capacitors like that I'm thinking that compressor is short lived, Are you plugged in to a pedestal?Low voltage will play havoc on ac units

[solutionsville]

That would suck. I have had the trailer only since March this year.

Thanks

[SlowrideHD]

If you need warranty work, I would suggest contacting an excellent and trusted mobile rv tech that is local and has dealt with Forest River branded units. Let them do the heavy lifting. You'll generally get a lot quicker and more effective repairs.

[solutionsville]

Thanks, I will look.into it.