Question about Dometic Rooftop RV Air Conditioner

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Brand new Duo Therm won't stay running

I just installed a new 13500 BTU roof A/C on my pre-wired 5th wheel trailer. This is a second air conditioner. When I fired it up, it ran and blew cold air for about 2 minutes and shut down both fan and compressor. The fan will still run in manual. I have got it to run again 2 times with the same results. I took the cover off the unit and the compressor seems hot to me.

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  • th155487 Jul 02, 2009

    It has local manual controls and is not hooked up to a remote thermostat.



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You really need an Ammeter to check this problem. Just because it is a brand new unit does not mean that there isn't a problem with it. Is it run off of a wall thermostat or manual controls? The compressor has a thermal overload switch on the top (under the plastic cover) that will take the compressor out of the circuit if it gets too hot. However, if the entire unit is shutting off, there is another problem. Selector Switch? Thermostat? Let me know what kind of controls you have and we can go from there.

Posted on Jul 02, 2009

  • Jeff Myers Jul 02, 2009

    The Compressor should feel hot if working correctly. It should be uncomfortable for you to keep your hand on it. Turn the selector switch to high cool, with the compressor running, turn the thermostat to the warmest setting. Does the compressor kick off? Turn the thermostat back to the coldest setting and see if the compressor kicks on. If you are running the AC and the fan and the compressor kick off but a breaker does not trip. Then I would say you have a problem with your selector switch.

  • Jeff Myers Jul 03, 2009

    If you have local controls on the unit, then the only thing that is going to make both the fan and the compressor stop at the same time is a loss of power to both. This can only be done through the selector switch. The switch controls power to the thermostat and in turn, the thermostat to the compressor. The switch also sends power directly to the fan motor via the capacitor. Check to make sure that the power connections are tight. How did you get power to the unit? Was the coach prewired?
    Sounds like it is a bad selector switch or loose wire on the back of the selector switch.

    Hope this helps.



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