On one of the very few cold days we had here in the Toronto area this winter, the dashboard of my 1999 A4 1.8T started clicking (for lack of a better word) almost like something was being zapped. Ever since then, I've lost the digital temperature gauge on the dashboard (the one below the tach and speedo that also has that little snowflake symbol when near zero celsius), my rear defrost won't work AND the A/C won't blow cold air.

Strangely enough, all three did come back for about a day recently, but it's back to dead.

I've checked all fuses that could apply but nothing is blown.

I think that maybe it's a loose connection or harness that somehow got fried when it was really cold.

Other than that, I have no clue. Any help would be greatly appreciated.

THANKS.

 

UPDATE: today, after posting and scheduling an appointment with a mechanic (Murphy's Law, of course), my temperature display is back, a/c blows cold air, and I assume the rear defrost is also back.

Does anyone have a clue what's going on?

 

No idea. Though, if you find out, please let us know! Thanks!

 

I guess no one still has a clue. I had a local mechanic hook it up to an Audi diagnostic computer today and it says everything is working fine - although it isn't. I still don't have temperature display, rear defrost and A/C. I don't get it .... and it's getting warmer again, and I'll need my A/C!

 

I think I've narrowed it down to either a faulty inside temperature sensor or a faulty outside temperature sensor.

Does anyone know where and how I can check these sensors? I think it may be a loose or cut wire somewhere.

FYI - a recent check with a VAG computer revealed no concerns.

 

I've got the Haynes manual. I'll see if there is anything I can find in there.

 

That would be great. I really appreciate the help.

 

I already check a A6 c5 that i was looking to buy with that problem. If the car cannot read outside air temp, it will not be able to show it to you and because it didn't know the air temp, it will not let the A/C work. The sensor is (i think) between the front bumper and the radiator. You can see it without removing anything. Open the hood and look maybe 4 cm in from of the radiator. Probably a connector problem or faulty sensor. The car I saw with that complaint (no reading of outside temp and no A/C) had a vag com code. If i remember well, it was in the AUTO hvac section. Do a "Auto-Scan" of your car with the vagcom.

 

I found it on ECS

http://www.ecstuning.com/Audi-B5_A4-...O-Ring/ES7330/

"This ambient air temperature sensor is located inside the front bumper. It controls the climate control, and is essential to maintaining a comfortable interior in your car. When this switch is malfunctioning, the climate control system cannot accurately maintain interior temperatures"