Question about Dometic Rooftop RV Air Conditioner

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My dometic 15k brisk-air cont. cycles on-off

My dometic 15k brisk air cycles on 8-10 seconds and off 40-60 seconds on low setting, eventually tripping the breaker on the camper. Power supplied to the camper has been checked and it is fine. Dealer states it is normal, and should only be run on high. I don't buy it. Any ideas?

Posted by fishweigel on


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Actually, the dealer is somewhat correct. In the hotter months of the summer, the rooftop units have a tendency to freeze up if not run on high cool due to the lack of air movement across the evaporator. If the unit fines on High/Cool, then run it in that mode but adjust the thermostat.

It should not however, cycle on and off that fast unless you have a bad freeze switch or the incoming AC is too low. If during that 8-10 seconds, the air begins to get cold and then it shuts off, then I would say you have a bad freeze switch. If it runs fine on high, but shuts off in low, I would say it is a lack of air movement.

Hope this helps,


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Posted on Jul 06, 2009

  • ASUcontrol Jun 28, 2011

    your getting me closer to the problem. I just blew $780.00 on a new air conditioner when I did'nt have to.



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I followed the advice that I found on many boards. I replaced the cap....although this needed to be done, it did not fix the problem of fast cycling which bogged my generator. Check the short duct from the outlet coming through the ceiling to the plastic cover inside....mind had come loose and fell down. This allowed cold air to blow on the sensor. I fixed with some aluminum and duct perfect now! Cheap and easy fix.

Posted on Aug 02, 2011



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Check the position of the thermostat sensor. It should be out in the path of the return air, not up against the cold air duct. Your install manual should show where it belongs. If it lies agains the cold air duct, it will short cycle.

Posted on Jul 19, 2009


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I agree with Tweak313. I would verify the capacitor and do a amp draw check on the compressor and the fan motor. Also, check all wiring and terminal connections.

Posted on Jul 08, 2009


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Does'nt sound like anyone has taken the most likely techincal explanation into consideration to me, I think you should have your start cap relay looked at. It's a little black box about an inch square inside the rooftop unit. It tells your fan when to turn on and off, it probably is shorting out.

Posted on Jul 07, 2009

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