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Marty, ASE Certified Technician
Category: Volkswagen
Satisfied Customers: 99
Experience:  Bosch Certified Master Technician with over 35 years experience in the automotive industry.
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I have a passat 2007 tdi b6 with climatic (manual)air conditioning.

Customer Question

I have a passat 2007 tdi b6 with climatic (manual)air conditioning. The compressor is a variable swash plate type compressor with a fixed drive pulley (no magnetic clutch to cycle it on off). The air conditioning was working sometimes and sometimes not over long drives. Just recently the symptoms changed to, work for a few miles then stop working and only deliver non refrigerated air. I read the pressure with my scanner tool and with it not working the pressure is 6.8 bar (standard ac fully charged and not compressing i believe) when it works the pressure goes up to 10.8 bar and even 12 bar sometimes. The evaporater sensor reads as 3 degrees c when working for a time and over 17 degrees c when not (in middle of heatwave here in uk). As it seems to reflect the temps correctly i assume the evap temp sensor is ok. Also the refrigerant pressure sensor is reading ok as no erratic readings and the pressure read reflects the operating state of the system. When it starts to compress i can see the gradual rise to compressed pressure. When i leave the car standing for a few hours and return, to get the fault i ususally have to start and run the ac a few times and leave car turned off for 10 minutes or so each time before the third or fourth start attempt will result in the ac not getting cold. I am a full time mechanic master tech myself just not on vw, and after a few hours of revising about variable swash compressors i thought maybe the regulator on the compressor was faulty. So i have replaced the compressor and it has 600g r134a in system. It is still faulty. I have noticed now that when not working the electronic fans under the bonnet do not operate but when the air con is working fine they both operate . I am not sure what the measuring block values are in ac heating systems data group 2 but the current reading i assume to be the compressor regulator control is at .82a most of time when not working and when working the current eventually stabilises at about .79 to .82a i HAVE SWAPPED ALL THE RELAYS AROUND WITH THE CORRESPONDING NUMBERED RELAYS in the fuse board under the drivers right knee area and have eliminated any of them as all had another to swap with and still air con faulty. Just spent the last 3 hours looking for wiring diags and operating principles of the fans and air con system as i am sure there is some module somewhere i cannot find . now i give up and need an expert to help me in my diagnosis. Remember this is a variable swash compressor as i am sure if you are vw master tech you will know this and it is manual air con system climatic i think it is called. Desperately trying to find answer tonight.
Submitted: 4 years ago.
Category: Volkswagen
Expert:  Shantal-Mod replied 4 years ago.


I've been working hard to find a Professional to assist you with your question, but sometimes finding the right Professional can take a little longer than expected.

I wonder whether you're ok with continuing to wait for an answer. If you are, please let me know and I will continue my search. If not, feel free to let me know and I will cancel this question for you.

Thank you,


Expert:  David-VAG replied 4 years ago.

Hello and welcome to just answer

Have you checked the fault memory for the air con system for any falt codes yet please?


Customer: replied 4 years ago.
sorry David. Waiting forCustomerto close question. Already fixed fault. Bought relevant wiring diags and eventually traced fault to mosfet in fans control module built into back of fan motor.
Expert:  Shantal-Mod replied 4 years ago.


I am sorry we were unable to assist you. As requested I will go ahead and close your question.

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