Wires to air con compressor?

[Greendon]

2003 Polo 1.4 Petrol 9N. 78K miles.

Background:

The air con hasn't worked for ages. The switch lights up, but there's no-one home. The recirc mode operates, and following the brilliant guide elsewhere on here to repair the V68 motor, the temperature is controllable, which it wasn't before. The fan operates on all speeds.

Took it to an air con specialist a couple of years ago who didn't even want to start working on it, on the basis that for such a low value car the cost could soon make it non-viable. I appreciate his not taking us for a ride.

Question:

A black and a red wire lead into the bottom of the compressor. I wondered whether this was the clutch solenoid, disconnected it and fed it 12 volts. No sound from the clutch/solenoid. I then discovered the supply to the connector is live with 12 volts all the time, whether the air con is switched on (AC light lit) or not. Was this productive troubleshooting? Can anyone suggest anything else I could check?

Thanks - Greendon

[RUM4MO]

It is not the supply for the compressor clutch - like compressors of old, that compressor runs at a low duty cycle when there is no demand for chilling the cabin air, this keep all the seals wetted with circulating oil mist carried round the system by this running at low duty as opposed to being "OFF" - by the way, this compressor type does not have a pulley clutch.

I don't know the exact function of that wiring, thermal protection maybe - just a guess!

So, back to your problem, horrible as it seems, why not take it along to KwikFit for their fixed price regas, if that reveals a leaking condenser etc then work form there is money allows.

Over time, a "good" ie still sealed as intended, A/C system will leak R134a from its seals and flexible sections of piping, as a guide to what is possible, my wife used to have a late 2002 Polo SE that had Climatronic and it never ever used "topped up" through its life with us from initial delivery to 104K miles almost 13 years later. The A/C when requested, always works okay as a chiller, thought that was in central Scotland.

Edit:- I think that these compressors work a bit like variable displacement compressors, though if that wiring assists that I don't know

Final Edit:- the belt that drives that compressor and other things, get protected from that compressor seizing by the compressor pulley being equipped with a shear coupling at the pulley assembly, so, why not remove the drive belt and see if you think that there is a slight hint of "load" when turning that pulley, if there is no slight hint of "load" then that compressor has already seized and that coupling has sheared.

[Greendon]

That is a highly informative and useful post!

I'll investigate the compressor shear scenario first, if the book of Haynes can tell me how to get the belt off.

Many thanks Sir.

Greendon.

[RUM4MO]

Getting the belt off? I seem to remember it involves fitting a ring spanner onto that belts automatic adjuster/tensioner and rotating the tensioner so that it moves in (against its return/tensioning spring) inwards the engine then flicking the belt off its pulley and then slowly easing the ring spanner back until the tensioner touches its end stop. This sounds a lot easier than it might end up, take care with the ring spanner as that spring is quite strong and the tensioner can move quite a long way, you might take a couple of attempts to get the ring spanner starting in the right position.

[slowdown]

HAVE THE SAME PROBLEM 2004 sdi, have fixed a flexible hose, had a regas and compressor hasn,t kicked in ,. an auto electrican looked at it and said ,looks like a bit of the end of the compressor is missing. and you have a constant 12volts supply. have just had a look and i can,t see any missing part .