I have a '97 A4 and live in Washington, DC where it gets humid in the summer.

The air conditioner in the audi is tied to the exterrnal temperature sensor in that if the outside air temp is less than the required temperature, then, do not tax the a/c, jut blow air from outside.

Now the problem. When the humidity gets high the extrenal temerature sensor misreads and slowly drops to -54 degrees. thereby shutting off the A/C abd attmepting to blow what the car thinks is cold air from outside. However, it is really 90-100 degrees out.

I replaced the extrenal temperature sensor to no avail. Is there another sensor I am missing?

Could it be the air mass sensor? or the Intake Air Temperature Sensor (G42)?

Any assitance in this from the Audi wizards I've seen in this forum is greatly appreciated!!!

Many Thanks,

Geno

 

im no Audi wizard but the aircon needs resetting (VAG.COM)

 

Does the sensor still read incorretly. You might have a wire that is shorting out or a bad connection.

 

I got the same exact issue on 2001 A6 2.7T just few days back, still figuring out what to do with it, meanwhile got this info from some website,
not a pro myself couldnt figure out the location of second sensor. I will greatly appreciate any help to identify the root cause!

"One is located just behind the grill in the front of the car and the other is located in the plenum chamber below the windshield. The AC unit reads the two sensors and displays the temp of the coolest one. This is Audi's attempt to get around an erroneous temp from engine heat.
Anyway, the sensors are negative temp coefficient thermistors. As the temp goes down, the resistance goes up. They should each read 1000 ohms at 25 deg C."

 

I know this one!
remove your cabin airfilter. then you should see the tip of the sensor.
Hadmine fail on my a4 and caused a LOT of aggravation.

on my a4 it was a tight squeeze but i got it changed without pulling the whole dash.

-richard