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Air Conditioner Compressor clutch

September 27, 2016, 08:44:29 pm

My air conditioner compressor clutch is not receiving 12V power when I turn on the A/C.  I have not yet started to chase down the problem as the engine compartment was too hot to mess with.  I just did an archive search of the forum and found a thread back in 2010 to which Bret Wolfe wrote about the high pressure and low pressure safety interlock switches as well as a relay.  My first suspicion would be the relay or a fuse, if there is one.  The basic wiring diagram I have does not address this circuit.  Can anyone tell me where to look for the relay or a fuse in my '99 U320 36 foot coach?

Thanks,

Richard

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Re: Air Conditioner Compressor clutch

Reply #1 – September 27, 2016, 08:50:55 pm

The dash A/C clutch circuit is in the wiring diagrams in your owners binder. Follow that. Starts at switch in dash, may go thru thermostat on coils, and goes thru various high/low pressure cut-off switches and then to compressor (or a relay, I forget). I do know a relay piggybacks on the circuit to run the condensor fan.

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Re: Air Conditioner Compressor clutch

Reply #2 – September 27, 2016, 08:53:08 pm

Richard,

The breaker should be mounted on you isolator panel. There should also be a breaker next to it for the alternator along with the relays that control the compressor clutch and condenser fan.
Your B-2126 drawing should show it.

Pamela & Mike

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Re: Air Conditioner Compressor clutch

Reply #3 – September 27, 2016, 09:16:05 pm

If you are low on Freon there will be no power to the clutch.

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Re: Air Conditioner Compressor clutch

Reply #4 – September 27, 2016, 09:36:09 pm

Or maybe a bad low- pressure switch.  Jumper the wires together and see if the clutch engages.

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Re: Air Conditioner Compressor clutch

Reply #5 – September 28, 2016, 08:15:43 am

Thanks so much for the suggestions.  My coach is back in storage right now but now I have a starting point for trouble shooting when I get back down to it. 

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