Question about Dometic Rooftop RV Air Conditioner

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Hard Starting Dometic Rooftop AC unit

My Dometic AC has trouble starting after it has inactive for a month or more. The fan will run, but the compressor will not fully start. It hums momentarily then stops repeating every two minutes or so. This will continue for up to an hour until it finally starts. There is a hot electrical smell while this is going on too. Once the compressor finally kicks over, it runs fine for the entire trip until it is shut down for another month or so. Is this a weak start capacitor or a bad compressor?
Thanks for the help,
Bruce Turrentine

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  • Bud D4 Nov 23, 2008

    I have a 1997 Trek, model 2830. which has a 3.6kw LP onen generator, we replaced the ageing 13500btu AC unit with a new Dometic 15000btu unit. According to the specs. the new unit drew the same amount of current during start up and running. Now when the new unit cycles to fast, less than 2 minutes, it drags the generator down and then blows the breaker on the generator. all works fine with shore power.

    Question: Will the start up kit help solve the problem? I think for the price it can't hurt.

    Question: Can I add some type of delay to the thermostat?

    Bud De Fore


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Sounds like your compressor is actually bad. if it was a capacitor, it would have either already burned up which you would smell smoke and you might see it come out of the vent and the compressor would no longer function, or the capacitor is completely dead. They don't always explode or burn up, sometimes they just short out internally.

the other question with the generator. you need a hard start capacitor kit. they come with a start delay relay and don't cost very much. it will prolong the life of the compressor and they are very easy to install.

Posted on May 09, 2009

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Just add a$10:00 hard start kit to the compressor.

Posted on Sep 07, 2008

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