Air con pump turning all time

[Koala119]

Hi All,
Wonder if anyone could help me out.
The wifies little polo, 1.4 petrol, 9N3 2006 plate.

Noticed that the air con pump just below the alternator is turning all the time.
Have operated the air con switch on the dash several times to see if it would stop but it will not.
Looking round you tube etc it looks like it has stuck / jammed on.
I cant find any specific vids on the Denso pump how to remove and strip the clutch unit.

The pump is a Denso 6QO 820 808. JP 6SEUI4C. NDI

Can anyone point me in the right direction on how to remove and check over possibly replace the clutch and coil unit on this type of pump please ?

Thanks

[littlepolo]

If that is driven by the aux belt you can expect the pulley to turn, but is the AC on (there should be a lamp indicator on the control panel)?

[RUM4MO]

Cars of this age started to have AC compressors that were being continuously run by the engine, the idea was that if they were run at a very low duty cycle, then oil mist would keep all the "rubber" surfaces "wet" and so the allowed/expected slow loss of refrigerant would be reduced, so good for global warming.
These compressors achieve that by having "variable displacement" and so the refrigerant pumping - by way of volume, gets sort of matched to the system's requirements - again reducing engine load - and so emissions.
The variable displacement is achieved by the compressor having a "swash plate" which gets moved along/within the cylinder of the compressor reducing/increasing its effective pumping volume.
Much later cars moved on from this and still apply a bit of this and also reverting to using a de-clutching drive pulley - so maybe the best of both worlds - and more to go wrong.

One last thing, as the AC compressor in your car is driven directly from the "front end drive belt", it has a rubber coupler built into the pulley so that if the compressor seizes internally, this rubber coupler will shear which will allow the front end drive belt, and it's other driven services to keep running - and not just break or throw off the drive belt.

[littlepolo]

Interesting, thank you. So what is the allowed/expected slow loss of refrigerant. Over what period of time would this likely lead to a non-functional A/C?

[RUM4MO]

I don't know the range of acceptable losses from a auto AC (auto used to describe that it is fitted to a moving vehicle and not auto by operation), there are a few "rubber" hoses to allow relative movement of one part with respect to another, the compressor has shaft end seals and there are "rubber" O-ring seals at every pipe join/junction - and none of these "rubber" parts are a 100% barrier to refrigerants. It is what it is and is considered to be acceptable.

[littlepolo]

Interesting. I am checking with a supplier for a A/C seal service kit. The A/C loses pressure, slowly, over time. A dye did not show and leak points