Hopefully someone can point me in the right direction, there is no power going to the aircon clutch to activate it, it works if I give it a direct feed and there is enough gas in the system. I have been studying the wiring diagram and the power for the clutch goes through so many components I am a not sure which end to start as I have yet to locate where all the components are in the car, all the fuses are OK. Any advice much appreciated.

 

Year, model, and engine?

Cheers
DD

 

Sorry I forgot, its a 1984 Sovereign 4.2
Thanks Steve

 

There "should be" a small, 3-prong thermal fuse clipped to the compressor bracket. Sometimes you'll find a car where it has been discarded. It'll have 3 wires:

1) Green/brown- 12v supply from the climate control system. Specifically from the Ranco thermostat. This wire should have 12v whenever the climate control system is "on". If not, check the inline fuse behind the RH side console cheek panel, clipped to the side of the HVAC case. This inline fuse is one green/brown and yellow brown wires. Or.....the Ranco thermostat is faulty. Or....there's a fault elsewhere in the control system. Check the other 3 system fuses.

2) Green- 12v from thermal fuse to compressor clutch

3) Black- from thermal fuse to the superheat switch at the rear of the compressor

The superheat switch grounds the thermal fuse, blowing it, if the system is low on freon. If the thermal switch is blown there will be no voltage on the green wire.

Cheers
DD

 

Hi Doug, many thanks for your detailed reply, its just info I need. I already found that there was no power at the thermal fuse as I was working back from the compressor clutch and was puzzled about the wire that went to the back of the compressor, now I know what it does so need to check its not going to ground and test the fuse with an ohm meter. And now I know there is a fuse I didn’t know about on the green/brown so I can check that.
Its a friends car and they are now away on hols for a couple of weeks so I won’t get back to the car until later, but I will report back what I find.
regards Steve