Audi Repair: Aircon fault, external temperature sensor, cabin air filter

Question
Hi Jan, got an Audi A6 1.9 TDI 130BHP over in London Uk,with airconditioning that wont work, although the heater and blower does. The local Audi garage state their computer registers a fault with the air quality sensor and one with the air pressure sensor.  One of these is behind the dash, another behind the bumper, and so a fortune in labour costs to even investigate. However, we had storms in the UK about 1 week ago and because of the car's blocked drainage, the front passenger footwell and presumably the engine comp. became soaked.  This is when the air con stopped working.  If the car is allowed to dry out, is there a chance of the air con restarting and if not - any ideas at all ??  Thanks - UK Jim...

Answer
Hi Jim,

Thanks for your question.  The air quality sensor may be in the same channel as the cabin air filter, maybe just changiung that filter will help.  Drying out the car is never a bad idea; however if the water shorted something out, it is not likely to get better when it is dry.  On the other hand, you never know.  If the dealer made the diagnosis like you state, then the fuses were obviously checked right?  There is a fuse for the AC compressor...  The sensor behind the bumper is an external temperature sensor, which you can get to by removing the bumper, which is only a couple of bolts.  It is worth checking the connections, although if you have an external temperature reading on the dash, this is the sensor it uses.  There is a pressure sensor in the freon line which checks that the refrigerant level is charged enough.  Is that switch good?  It should be fairly easy to get to.  Let me know what you find,  Jan