What would cause the outside air temp on the dash to drop to -25 than slowly climb back up to the 85 it was. It has happened three times now over this summer. You will be driving along and the ac will stop. Look down and see the temp falling. After any where for 5 to 15 minutes later, it starts climbing back up. This is a pain because the ac stops working.

 

Air Temp Sensor Prob bad. $10.00 fix is worth a shot if you can get in there & DIY

Audi B5 A4 Quattro 1.8T > Climate Control > Electrical > Sensors > ES#2500959 Air Temperature Sensor - Priced Each - 4B0820539

 

If it is not the sensor (good bet), then it may be the sensor's wiring.

 

Where is the sensor? I can' t seem to find it.