View Full Version : A6 a/c diagnosis

08-06-2010, 10:49 PM
Been spending some time recently trying to solve an a/c fault on the wife's 1.9 tdi AHU engined 1997 A6. The relays, fuses and wires seem OK and the fans work with the engine hot. There is a new compressor recently fitted so it should be well gassed etc.

I can get this to engage by shorting out the low pressure switch but the fan does not come on as expected. However if I short out the high pressure switch the the fans kick in but not the compressor. There is another pressure switch(?) near the high pressure on and is at the side of the evaporator which sits in front of the rad but shorting this has no effect

The heating switch on the dash gives an error code on the low pressure switch but I still don't want to replace this till i know for sure. The local a/c specialists seem to pressure test and refill and leave the other stuff to the auto-electricians.

I can find any evidence of a VAG com connector in the car(?) so have less to go on than the slightly later models. Apparently pressure switches can be removed without emptying the system so it might be possible to try out a new value from a helpful source.

any suggestions are most welcome


08-06-2010, 11:47 PM
I think the connector port is in the fuse box housing under the bonnet, drivers side near/under the windscreen.

I havent checked on mine, but will and try to confirm