Chassis A/C Electrical problem

[hrbuchanan]

I have a 2004 Monoco Diplomat. The A/C is no cooling. Found that the compressor clutch is not engaging. Can hot wire the clucth and compressor works but needs to be charged, A/C compressor clutch fuse and relay is good. Condenser fan does not come on. Anyone have a idea, Most of all where can I get a wiring diagram for the A/C circuit. I can do the testing just need a wiring diagram.

[twinboat]

Low refrigerant will cut out compressor operation. Safety feature.

Non working condenser fan will cause high refrigerant pressure and leak. Need to fix that first.

Once fan is fixed and running, as you fill system clutch should engage.

[Old Scout]

....most automotive-style A/C systems use a trinary valve [switch] that measures 134a pressure in the system--too low: no compressor start; too high: cuts off; just right but increasing: turns on condenser fans [if so equipped]. So if system "needs charging," compressor wont start and fans wont run......

[YC1]

This is for my 08 so your mileage may vary.

Exact symptoms as mine when the coolant gets low. Long hoses so it may take quite a bit.

Is there a "site glass". A device in the system with a small clear piece of glass. I can see bubbles in mine when it gets low.

I cannot remember if I have to bypass the protection switch to fill it or if it will take in the gas without doing that. I do remember bypassing it for a test.

[hrbuchanan]

Thanks for your response. I did find the problem. Had a bad connection at the evaporator temp control switch. Was able to get evey up running and charged.

[Quincy]

It should take the charge even if it is off and when pressures get close to normal the comp. should start when the Low Pressure Switch engages.