Air Con - Gimme A Clue!

[JohnR]

Have just purchased a 52 plate TDi ghia. Seems to run very sweetly, but needs a bit of tidying up (cosmetic) and having now gone over it there is no cooling although there are no fault indications and everything on the panel seems to work otherwise. :wacko:

 

I've ordered a TIS CD, which should arrive in a few days, but can someone give me a quick leg up? As I see it, the best scenario is just that its lost some gas pressure so the clutch is not pulling in. Worst scenario is the nightmare rebuild.

 

What do I need to test the gas pressure, and how do you access the compressor and check clutch function? If anyone has any info to save me some time (a fault finding tree?) I'd appreciate it!

 

Cheers

John

[MrT]

You can tell if the clutch is engaging as the centre part spins when it is engaged. The outer pulley always spins.

 

You can test the pressure with a pressure gauge on the low pressure air con filler. However the most common standalone pressure gauge available from outlets like Halfords does not work properly on some Galaxies as the centre pin in the gauge is too thick to fit in the hole in the air con filler. The gauges on filler tubes from Halfords fit.

[sepulchrave]

I thought that low gas pressure was indicated by a flashing display, is that not the case on Mark II's?

[MrT]

With over or under pressure detected by the pressure switch the climate control panel should flash on start-up on the MkII (well it did on mine).

 

However the system will normally lose cooling power due to a lack of coolant before the pressure switch detects it. The clutch will be engaged in that situation, but there is not enough pressure to provide cooling. That is why you need to look to see if the clutch is engaged. If the clutch is engaging, a partial coolant loss is the most likely cause. The centre of the clutch (when the engine is off) should be turnable against a slight resistance by hand, if it spins freely or is jammed there is something seriously wrong with the clutch/compressor.

 

If the clutch is not engaging check the power to the compressor. There are only two wires to the compressor, +12V and ground, you have power when the compressor should engage and no power when disconnected. No power here means look in other areas such as the wiring, controls and temperature sensors.

 

If you have power to the compressor and the clutch is not engaging, the clutch field coils are likely to have gone. In this situation you are probably better getting a remanufactured compressor (