My bus has a rarely used older unit that ran perfectly until last week. I noticed that during the cycle to start the compressor, it slowed down for about 10 seconds, compressor does not start, then fan resumes normal speed for a couple of minutes. it then lugs down again (fan also) for the 10 seconds or thereabouts, thens resumes normal fan operation for a couple of minutes or so. Its like it cycles for the compressor and when it doesn't start, it waits a certain period then does it all again. I was working in the bus when it did it and noticed it immediately.It worked so normally I have a hard time thinking its the compressor.
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Re: compressor wont start
It is probably a failed run capacitor for the compressor. Without the capacitor, the motor can't even try to run, but it will draw extreamly high amperage until it trips the thermal overload (avarage trip time 5-10sec) after it has a few second for the safety to cool off, it will try again. Either that or the compressor truly is seized
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Your unit uses both the capacitor and a contactor (relay) to start your compressor and motor. With the indications you are giving it would either be the capacitor or the contactor - and since you have already changed the cap - then replace the contractor!
NOTE: We always recommend that you change the capacitor and relay at the same time, because they seem to fail at about the same time.
this appears to be a stuck relay or contactor . follow the wire back from the fan and locate the contactor or relay slp it and see it it comes lose. ?? this does not mean it will solve the problem as you will still have to repalce any part that is causing it.. Hope this helps let me know Jon
Take it back or call Sears. A 2 week old unit should not do that. I'll assume the settings are right like set on AC Auto or Max cool and not just fan. Are the coils icing or were they icing behind the filter? If not, I think it may need to be serviced.
unfortunaletly the hartd start is a "last resort" and you will probably need to replace the compressor/unit... (however I have had luck physically jarring the compressor during the instant I applied power to the compressor.. sounds silly, but I have had it work more than once..) hope this helps
First of all, clean your outside coils so that you are assured of good cooling air. The compressors have an overtemp device that is usually internal to protect them against heat. If you have an air compressor use it to blow out the coils good. If the compressor will start, the capacitor is good so it sounds like a cooling problem with the compressor
Hello kamper2 - Sorry for the delay in answering. I had a response prepaired but something cleared it on me about 2AM last night and I just couldn't think any more. Sounds like your problem is similar but different. I don't think you have to spend any more time on the roof looking at the roof unit. I have been working with a tech and Dometic for over 6 weeks. Right now I am running my A/C on an extension cord out my window and over the the power pedestal for power. The 12 VDC to the A/C circuit board is coming from a car battery sitting on my kitchen floor. The communication cable is a 25' telephone extension cord draped over my kitchen slide over to the CCC. Last week end I turned off all power to the trailer (110VAC and 12VDC) and sat here all day running just the A/C. It shut down 6 times. This was an effort by Dometic to eliminate RF energy affecting the microprocesser on the A/C control circuit board. Apparently the CCC and A/C control circuit board have some idiosyncrasies that aren't well explained. I also have an extended warranty on my A/C with Dometic. I'm thinking they believe RF energy may be picked up via the communication cable and affecting the microprocessor. Do you have a cell phone, wireless router for your computer or telephone or something that may put out noticeable RF energy? If you do, turn it off for a while to see if that may be related to the shut down's. I'm still working on my problem and no solution or reason yet. The circuit board in my A/C has already been replaced. I am assuming you do not have an icing problem with the problem A/C. If for some reason you decide to replace the communication cable from the CCC to the A/C circuit board, be aware that a typical telephone extension cord will not work. You must replace one of the plugs so the wires are straight through (pin for pin) and not reversed as the typical telephone extension cord is. Good luck with your detective work! azbill375