VW Golf - 2002 1.9TDi - PD - Air conditioning not working.....

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Wed 31 Aug 2011 23:30
VW Golf - 2002 1.9TDi - PD - Air conditioning not working..... - Railroad.

It was working but it stopped and hasn't worked since. There is no supply feed to the compressor when the system is switched on. If a 12V feed is supplied to the compressor the system then works perfectly well and gets cold very quickly.

The control unit is located behind the front bumper on the N/S. There are three permanent live fused feeds plus one ignition fused feed to the control unit which are present and correct. The control unit has a good earth. There is a 12V feed from the A/C switch at the control unit. The fans will work on both slow and fast speeds if the terminals at the control unit plug are bridged. The ambient temperature sensor measures 1500 ohms taken from the control unit plug, and reduces if I blow on the sensor thus suggesting it works properly. The high pressure sensor is neither grounded or live suggesting it's working. Placing a direct 12V feed at the cooling fan switch in the radiator will switch on the relay and operate the cooling fans. Checking the communication from the engine control unit isn't so easy. Despite all this the output from the control unit to the compressor does not becove live when the A/C is switched on from inside the car. Apparantly the control unit has been replaced so I have been told, so if anyone has any ideas I'd be grateful.....

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Thu 1 Sep 2011 15:36
VW Golf - 2002 1.9TDi - PD - Air conditioning not working..... - Peter D

A diagnostic code read may point you in the right direction. Regards Peter

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Thu 1 Sep 2011 20:34
VW Golf - 2002 1.9TDi - PD - Air conditioning not working..... - Railroad.

It might Peter, except that it doesn't have climate control and therefore no HVAC controller. I have VCDS in any case. The control unit that I referred to also houses the two relays for the cooling fans.....

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Fri 2 Sep 2011 23:25
VW Golf - 2002 1.9TDi - PD - Air conditioning not working..... - elekie&a/c doctor

As the car is fitted with manual a/c ,then there is no diagnostic check for the system as already mentioned.Most of your tests seem good,however the test for the pressure switch needs to be more accurate as this is an electronic device and not a regular on/off switch.There should be a 12v supply and earth to the switch ,with the signal voltage on the white wire (usually)back to the fan/compressor relay.Do the cooling fans fire up when the a/c is switched on?If not,then I would suspect this pressure sensor at fault.I recently looked at a Bora with exact symptons and pressure switch was the culprit.Also be warned,when replacing this switch,it is imperative to support the aluminium spur pipe otherwise it will rip off.hth

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Sat 3 Sep 2011 16:48
VW Golf - 2002 1.9TDi - PD - Air conditioning not working..... - Railroad.

Thanks for that. I am a bit suspicous of the high pressure sensor to be honest. I'll change it and report back.....

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