AC Compressor Not Working: Troubleshooting Guide (27-03-2006, 22:24)

Hello everyone,

"The manual air conditioning system in my Audi is defective. I tried to query the control unit for the air conditioning compressor using VAG Com 512.2, following the repair manual and using address 08. The response from VAG Com is: 'Controller uses unknown protocol. Protocol keyword: FF01'."

Could it be that VAG COM is unable to access the control unit? If so, then the unit is probably defective. Where exactly is the control unit located?

Feel free to email me for details.

https://shop.dieselschrauber.org/en/contact_us.php

Hi! Regardless of the diagnosis: have you checked the system pressure in the air conditioning system? If you bypass the pressure switch and the compressor then starts, the air conditioning system needs to be refilled and checked for leaks. Best regards, Hartmut.

Yes, the manual climate control system in the Audi 80 is actually diagnosable and can even access some data blocks. The control unit is located behind the storage compartment under the steering wheel and looks like an oversized relay.

First, I would check the fuses. Second, you could try applying voltage directly to the solenoid valve; you should then be able to hear it engage. If that works, check the wiring harness.

"As Harmut K. wrote: Definitely not enough refrigerant in the system! If the compressor were to continue running without refrigerant, it would soon break down... So, take it to a climate control service!"