Dometic A/C unit 13500 BTU model # 600315.321
(Key West, FL)
Question:Monoco Knight Motorhome 2001. Front A/C unit works fine until it reaches the set temp then the fan shuts off but I keep hearing something running. It runs until the circuit breaker pops about 10 minutes. I suspect that it is the compressor that is running. After the breaker pops or if I shut it off before it pops, then turn the breaker back on the air works fine. I think the problem is in the relay control board part # 3107541.009.I can also pull the white plug out of this relay control box and my compressor shuts off. There is a relay in there that controls the compressor an N/O Relay K4 per the wiring diagram. The only thing is is that the diagram does not show how the coil of this relay is controlled. I cannot figure out from the wiring diagrams that I have if something else is causing this relay to stay closed. It just seems to easy to say the relay is just sticking and replace it.
You have done an outstanding job in your diagnostics and have provided me the most valuable information ever to answer a question on my Web Site and I thank you.The problem your having is a common one and your correct in that the relay is sticking on your control board and you need to replace the board.The relay is controlled from the wall thermastat and is on your 12V system. You were also correct in saying the answer was just to easy and you have to replace the board. Have a Great day Thanks for the Question Good Luck,
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