OK, I'm sure there's an easy solution to this problem, the Aircon on my 01 Octy doesn't seem to work, bought the car just before xmas so not really had the weather to find out till now!

The self-diagnostics on the climatronic doesn't show any stored codes, neither does VCDS, all the fuses and mag-clutch look ok, and the Hafrauds pressure test says 'normal' so I'm not thinking it's low pressure or mechanical, more electrical! A quick check on connector T4a by the battery shows a good earth, however I cannot get a 12v on pin3, all the fuses are also OK.

Questions....

1) Where does the power feed to T4a run? (the wiring diagram says it goes to a 14pin connector by the radiator fan control unit but where is it?!?!?)

2) Any other parts to check out that may be causing the problem?

Have you checked the fuses on the top of the battery?

Have you checked the fuses on the top of the battery?

Only Visually, would it be worth double checking with the meter?

I would get it recharged as its probably low on gas as mine was rubbish when i bought it last year till i recharged it

Not really. If they're blown, you can tell just by looking. They will have melted.

The fan control unit is underneath the battery. AFAIK, the climatronic sends a signal to the fan control unit, which turns the fans on, and then turns the compressor on. Do the fans spin?

Check with the meter on my way home just now, all looking normal, not sure if the fans cut in under climatronic control, but can check tomorrow, I know pulling the clutch fuse turns both fans on though (ignition off).

I'm guessing the "easy" way to the fan controller is battery and tray out?

Yup.

Good guide here: http://www.nime.co.uk/content.php?fancontrollerinstall

There's also a guide here on how to diagnose the AC on a 2000 Jetta. I presume the octy will be similar, if not the same.

Just found a pinout

http://pics.tdiclub.com/data/529/J293-a4_fancontrol_module.pdf

Yup.

Good guide here: http://www.nime.co.uk/content.php?fancontrollerinstall

There's also a guide here on how to diagnose the AC on a 2000 Jetta. I presume the octy will be similar, if not the same.

Cool :-) Guess I know what I'm doing this afternoon after work now!

OK, there's now a 9V feed from the Fan controller, took it out and reseated all the connectors, must of disturbed it when I changed the battery before xmas.

Still doesn't seem like it's cooling very well, is the consensus that a re-gas is needed now? (not sure if it's ever been done before)

Yes,probably needed a re gas. Remember you do not have to wait for nice weather to run the aircon,it's best to run it often as it prevents the seals from drying out and causing leaks.

Booked the car in next Friday to be looked at by an indy garage, so hopefully it'll just be gas (or something cheap!)