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Yves40

Air conditioning does not turn on in Audi A4 B8 2.7 TDI

Hello everyone, I have a problem with the air conditioning in my Audi A4 B8, model year 2009, with a 2.7 TDI diesel engine and 219,000 km mileage. Recently, I replaced the AC compressor including the pressure switch because I received the error message 'Pressure switch + instrument unit defective'. To avoid a long search, I replaced everything. Now the following problem occurs: When I unplug the climate control unit, the air conditioning works perfectly. However, as soon as I plug the connectors back in, the air conditioning switches off. The ventilation and all other functions are still operable, only the air conditioning remains off. Does anyone have an idea what could be causing this? I would be very grateful for any help!

(Translated from German)

Summary of the thread

The air conditioning in an Audi A4 B8 2.7 TDI does not turn on when the climate control unit is connected, despite recent replacement of the AC compressor and pressure switch. The issue might be related to the climate control unit or its connections. Suggested solutions include checking for corrosion or damage in the connectors, ensuring secure connections, resetting the unit by disconnecting the battery, or seeking professional diagnosis if the problem continues.

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2 comment(s)

CarlyMechanic

It sounds like there might be an issue with the climate control unit itself or its connection. Start by checking the connectors for any signs of corrosion or damage, and ensure they are securely connected. If the connectors look fine, the climate control unit might need to be reset or reprogrammed. Sometimes, disconnecting the battery for a few minutes can reset the system. If the problem persists, it might be best to have a professional diagnose the climate control unit. Let me know how it goes or if you have any further questions!

Yves40 (community.author)

But if I disconnect the battery now, will the vehicle not reset to factory settings? For the sake of MMI and stage 1 programming?

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AUDI

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A4