Air Con Problem

[SimonKD]

Typical, air con has packed up today on the way up to Tatton Park just when I needed it.

Anyway, with the cold fan on when I press the air con button the blue LED comes on and the control box in the passenger footwell is making a clicking noise. The problem is their is no 12V signal getting to the air con clutch.

The ribbon cable and the other multi pin connector on the control box look ok.

I'm already thinking I may have control box problems. Are their any serviceable componants inside? Is it just a relay inside the control box that puts a 12V feed to the air con clutch? Are these boxes still available to buy.

Sorry about all the questions. Has anyone got any ideas?

Going now to check continuity between wire in engine bay on clutch and multi pin plug in passenger footwell.

Any advice appreciated.

Regards
Simon.

[JensenA]

First thing to do is have the gas checked - too little gas and it will keep trying to cut in, but never will.

[SimonKD]

Cheers Alan

So what you're saying is a low gas pressure will stop the control box sending a 12V signal to the air con clutch?

I've checked for continuity between control box plug and the other end of the wire in the engine bay and it's ok.

Regards
Simon.

[mikesr]

There are two relays in the control box.
Turning the switch on closes the first.
Then there is a whole rigmarole of stuff via the pressure sensor on the drier bottle, the rheostat and the ecu that should result in the ecu closing the second relay and putting 12v into the air con clutch.

I traced the whole thing out a while back see this thread for the details.

End result for me was electrics fine but no gas in the system.

[SimonKD]

Thanks each

Fault finding will resume in the morning.

Regards
Simon.

[Ireland]

SimonKD said:

..... a low gas pressure will stop the control box sending a 12V signal to the air con clutch?

Yes