Audi A3 8L AC Not Working - Repair Guide

Hello.

I'm having a problem with my A3; the air conditioning isn't working.

The gas has been refilled, the compressor has been replaced, and the diagnostic device shows no errors.
The three fuses on the battery, leading from the control unit to the compressor, are only showing around 10 volts. I replaced the control unit, but the problem is still the same! When I supply the compressor directly with 12 volts, the clutch engages. I tested the wiring harness by piercing it after the connector to the control unit, and I'm still only getting 10 volts.
And the second fan is running constantly, even at the low temperatures. I think it should only turn on when the air conditioning is on.

Has anyone else experienced a similar issue, or can someone help me?

Sincerely,

In this case, you really won't be able to make much progress without VCDS.

Are you aware that the compressor doesn't start below +5°C?

However, if the fan is running, the temperature must be above 5 degrees Celsius, or...or...or. VCDS would be helpful in this case.

So, if the fan for the air conditioning condenser is running constantly, to me that sounds very much like a kind of emergency mode from the air conditioning control unit.

What kind of "diagnostic tool" did you use?

But, as mentioned before, VCDS is the right tool to use to move forward with this.


I would suggest, in your place, simply checking the connections of all the sensors for the climate control system to see if the sensors, such as the refrigerant pressure sensor, are providing plausible values, etc.