Dometic 12k Air Conditioner

[nofd843]

I have a 31 foot Hunter with a 12K Dometic Vector Air Conditioner. THe other day i noticed it did not sound like everything was running and it was putting out warm air.

Now, when the A/C tries to start you can hear the compressor (that is what I do not think I was hearing the other day) try to start, it gets about three pumps and then locks up. If you have a light plugged in to the 110 side of the power (the boat has both ac and dc lights on it) the light goes dim when it starts and stays dim until the compressor makes a clicking sound, like a relay is releasing.

Would this be the starting capacitor going bad, not able to give enough power to get the compressor spinnig at full speed or do you think the compressor has broken inside and is jamming?

Any ideas would be helpful.

Jeff

 

[dakno]

It sounds like u need a " hot start or jump start capacitor", these r made 4 a/c's that r getting tired or dont have enough voltage 4 start up. Most a/c compressors require 50% or more voltage 4 start-up than what their running amp requirement is.

 

[kloudie1]

Could be low voltage from a bad connection.. could be on boat end or marina end of the shore power cable or connectors.. Could be the breaker on the boat or the wires going there, or the compressor “run” relay or the capacitor getting weak.. If it used to work and it isn’t very old, I’d suspect and check all the connections first.. don't overlook the connections on the breaker in the electrical panel.. Could be the compressor itself too, but that would be the final part of the troubleshooting.. Ohhh.. Make sure that you have excellent water flow through the condenser too.. doesn’t sound like that is the problem but I don’t know that particular unit .. Good luck ! Gonna be warm troubleshooting that one

 

[nofd843]

...If the capacitor was going bad or it wasn't getting enough amperage would the compressor still turn over? or would it just hummmm? I guess this is where I am confused the most. I was thinking if the capacitor was bad the compressor would not have enough amperage to turn over since the initial starting amperage is almost 60 amps.

 

[kloudie1]

Did it work fine before? Did ya do any work around the unit or its connections? How old is it?
Yes, a bad capacitor can do that since it kinda’ kick starts the compressor.. but that is only for a short time (less than a second typically; most are necessary for continued running too; if the compressor gets a little rotation before humming, probably not cap.. I am going by your description)(yeah I know about phase shift) ..It is quick and easy to change a cap and not too costly ($25), so you can try that ..?? If the connections are bad, there will be enough voltage drop to not have the continued power to run the compressor motor after it kicks over a little.. The bad connection would get pretty hot after a start try, so you may be able to quickly find it by touch .. PLEASE remember to disconnect the shore cable before going around touching things! Uhhhh why yes, that scar on my finger looks like a result of an electric arc!

 

[nofd843]

It is a 2006 sailboat, the connections look good and it worked fine two days ago. I have ordered a new capacitor and starter pack. I will also double check the back side of the power panel. Just worried it might be the compressor, since it gets a couple pumps out and a little pressure before it sutters and stops.