Dometic Rooftop RV Air Conditioner Logo
Posted on May 13, 2008
Answered by a Fixya Expert

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Dometic a/c, duotherm thermostat, turns right back on after it reaches desired temperture.

I have a dometic 13500 BTU Roof mount a/c. It is set up with the duo-therm analog thermostat. The system cools fine. The problem is that the a/c gets down to the right temp, then it turns off like it should but turns right back on within a few seconds. Any help would be greatly appreciated.

  • 4 more comments 
  • 1Tree Jun 07, 2008

    I have that same problem, although it takes more like 1/2 minute to 1 minute. And since it was working, but then stopped with nothing else changed, the suggestion makes no logic at all.



    I have more than 40 years of experience in electro-mechanical service work and while it was not on RVs I am a reasonable competant trouble shooter. I suspect that my thermostat is the problem.

  • booregard Jun 19, 2008

    My problem is just the opposite. You turn it on and it runs for about 4 or 5 minutes and then shuts off completely. Will not start back up on the AC side. Will work on the fan side. I'm puzzled. Brand new unit, even went back and had the company replace the first one. Same problem. Any suggestions.

  • wind_32920 Jan 16, 2009

    I HAVE THE EXACT SAME PROBLEM. WHEN IT COMES BACK ON THE A/C GROANS AND IF USING GENERATOR IT OVERLOADS

  • axbow May 15, 2009

    I have the same problem as Super Troop. Compressor tries to come right back on after achieving set point. If on shore power, it will groan for a few seconds, stop trying for a minute or so and then kick back on - and the cycle repeats. Dometic dealer has fixed cold air leaks, blocked off air outlets near the thermostat (analog), checked and blessed the capacitors, refrigerant levels, drains and found no icing issues. They have no clue what the problem could be and are at a loss. Anybody??

  • Anonymous May 23, 2009

    I have this problem as well, except when the compressor tries to short cycle it doesn't have the power to do so, it tries a couple of times and then eventually blows the circuit breaker.

  • Crystal Anderson-Frazier

    I was told this was normal. It's your unit cycling through the fan mode

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  • Posted on Aug 08, 2009
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I have a dometic 13500 BTU Roof mount a/c. It is set up with the duo-therm analog thermostat. The system cools fine. The problem is that the a/c gets down to the right temp, then it turns off like it should but turns right back on within a few seconds. Any help would be greatly appreciated.

  • Kessler Sep 07, 2010

    Did you ever get this figured out?

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  • Posted on Aug 10, 2009
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Air conditioner worked good yesterday, today not blowing cold air, fan runs but compressor kicks off in just a few seconds. Also probably second problem, thermostate must be set at 90 to get a 72 degree cool.

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  • Posted on Aug 09, 2009
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For everyone with an RV rooftop a/c install a Supco Relay & Hard Start Capacitor (cost around $15 with shipping on ebay) and you will find your a/c performs and cycles MUCH better than with the OME capacitor alone. Even if you aren't experiancing the problems some of these people are reporting, it will make your unit last longer as it takes a lot of stress off the compressor. No, I am not a salesman for these things! I had problems with my a/c cycling and shutting down my generator and this solved my problems. I don't even notice it cycle anymore on shorepower or generator.

  • Anonymous Jan 28, 2013

    Where does the Supco Relay& Hard Start Capacltor mount in the AC?

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I discovered that the drains for the catch basin under the cooling coils were both plugged up. After I cleared them out it seems to be working properly now. I suspect that it may have been frosting up.

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  • Posted on Nov 03, 2009
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I solved the problem this weekend by removing the front cover, it appears that the control switches are in a bind. The heat and cool work fine now.

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The thermostat usually has wire that reads the temp in the room. The wire runs through the wall and can pick up heat from the wall. Put a piece of insulation around the wire where it comes through the wall and leave only the end of the wire exposed.

  • drnuklfunky Aug 17, 2010

    the problem is in the t-stat. the antisapator is set to low.

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  • Posted on May 31, 2008
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Check for a heat source near the thermostat. Try adjusting the louvers so the cold air is not blowing on the location of the thermostat. Sun shining on the outside wall in the area of the thermostat on the inside wall will also affect the operation.

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