Dometic Air Conditioners

[mlhjr1]

I have a 2002 CC Intrigue with two Dometic 13500 btu roof air conditioners that until recently both worked fine. However at a recent rally (and hooked up to 50 amp shores power) both air conditioners quit cooling. My thermostat has a setting for Mode, Fan, Up, Down, and Zone. The problem is: Sometimes, when I turn the air conditioner (either front or rear) ON, set to COOL, and fan to AUTO, nothing happens, yet if I switch the fan from AUTO to LOW or HIGH, the air conditioner comes on, but does not blow cool air. One time I left the air conditioner on COOL with the fan set to LOW and after being on for a couple of hours, the compressor came on and it started cooling. I left it on for two days and it cooled like it was supposed to do. However, after turning the AC off and letting it stay off for several days, the problem started all over again and neither AC compressor would come on line and start cooling. I took to RV to a motor home dealer and left it with them for two days. All of this time both AC's cooled as they were supposed to do and the technicians at the RV shop said that there was no way that they could trouble shoot the problem as long as the units were performing o.k. The even called Dometic and talked to their technicians about the problems and was told by the Dometic technician that the problem was somewhere in the DC circuits, such as a loose wire; bad florescent light ballast; dc fan motor, switch, etc. When I returned home from the RV shop and hooked up to my 50 amp shore power, neither air conditioners would cool. Several days later I turned both air conditioners ON and each one cooled as if there was no problem. Again, after letting both stay on for a couple of days, I turned both off. Since that time, I have tried turning them on, but have not had any success with the compressors coming on line and cooling. Only the fans come on and blow uncooled air. Has anyone experienced a similar situation with their air conditioners? I need help in solving this problem and would appreciate any suggestions as to what is causing them to sometimes work o.k. and the next time will not work.

[RJay]

Have you tried to run the air conditioners off the generator?

[Route 66]

Quote:

the Dometic technician that the problem was somewhere in the DC circuits, such as a loose wire; bad florescent light ballast; dc fan motor, switch, etc.

I agree that "dirty DC" or impure DC can cause Dometic ACs to have a mind of their own.

My front AC had the same symptoms and more. The cause was never found, but a 110v AC to 15v DC converter was installed to supply 12v DC to the Dometic system and everything instantly returned to normal. Never had another problem after that.

Newmar used satellite system "brick" similar to the power supply for a laptop computer.

[gripper]

Your problems could also, be the thermostat. I just posted "My Persnickity AC Thermostat", in the "General Discussions" forum, stating the continual problems that I had with my AC's. The contacts within the thermostat must get corroded and do not make good connections at various times. MY problems were/are, intermittantly, just like yours.

[RV Wizard]

I recommend you first clean the data cable connections at the thermostat and where it connects to the control board (or box). If this does not correct the problem, see if you can find someone with a like thermostat you can test with. Be sure to first reset the thermostat and then see if it operates the units properly. Let us know what you find.

["007"]

Welcome mlhjr1 to irv2.
Here is a PDF explaining your AC's operation.
When you first put on your AC's it may take a good 2 minuets before compressors will come on. If your using Gen power it will have a delay, than AC's to add to it.