Vauxhall Astra Air-con relay

go back and have it rechecked I reckon it will be down on gas, this will stop the pump clutch getting power

In my experience with having faulty aircon in Astras, if you push the switch and the light comes on and you hear a click but nothing happens then it is out of gas. Usually when it is leaking out the early warning is having to wait a few seconds for it to get going once the switch is pressed. I would take it back again. What happens if you take a wire from the positive terminal on the battery to the pump? Try that. if the garage showed you it working, or you have used it since and it has stopped working then it's a leak or electrical problem. If they lied about testing it and just filled it up then get it back over. The gas needs to be taken out, then a dye put in and the aircon run for a while before using a uV light to check for leaks. I never use the aircon anyway, it makes the car use far more petrol and slows it right down. Maybe it's better in a diesel.

Thanks for the responses. The garage did demo the air-con working and it did get the air very cold! They did also put the UV dye in at the same time but could find no trace of it leaking out in the first 20 mins or so with it running. It stopped working fairly suddenly later the same day but I haven't had chance to get back to the garage with it yet. I had a look with a UV lamp that evening and could find no sign of it all having leaked out.

A work colleague had a quick look at it yesterday (reasonably clued up with auto electrics just not the specifics of the Astra) and observed the issue of no voltage reaching the pump clutch, even though the light in the car comes on to suggest the air-con is active. We concluded that it was likely to be the relay which controls this not working. Or is it not quite that simple? Is there a sensor involved which only engages the pump if it detects sufficient pressure of gas?

I think a trip back to the garage is in order, however I thought if it is likely to be a minor electrical problem (which wouldn't be covered by any guarentee of their re-gassing work) then it would probably be cheaper to try look into it myself first. New relay =3D about =A34.00... full diagnostic service of air-con system at garage plus new relay =3D probably more like =A350, I would imagine.

I just don't know which one to try changing first!

Thanks again for the replies,

Ben.

Yes, there is a low pressure cut out switch. If you or your colleague can locate this, try bypassing it *briefly*. If the clutch then engages the chances are that there is no gas present.

If it wasn't working, then it was refilled and worked, now it's not working again then I would say it's most likely to have a leak.

Chris.

A work colleague had a quick look at it yesterday (reasonably clued up with auto electrics just not the specifics of the Astra) and observed the issue of no voltage reaching the pump clutch, even though the light in the car comes on to suggest the air-con is active. We concluded that it was likely to be the relay which controls this not working. Or is it not quite that simple? Is there a sensor involved which only engages the pump if it detects sufficient pressure of gas?

I think a trip back to the garage is in order, however I thought if it is likely to be a minor electrical problem (which wouldn't be covered by any guarentee of their re-gassing work) then it would probably be cheaper to try look into it myself first. New relay = about £4.00... full diagnostic service of air-con system at garage plus new relay = probably more like £50, I would imagine.

I just don't know which one to try changing first!

Thanks again for the replies

There are two relays which control the clutch- one is behind the dash /glovebox mounted on the plenum casing, you should hear this click when you press the switch and the light comes on. #

The other is in the engine bay fuse box, this is under ECU control

If the fans are not coming on then check the fan relay, if they are coming on then you have one of two problems.

If when breifly shorting the LP switch and the relay clicks, clutch engages and then rapidly starts chilling then consider you are ok on gas, either replace the LP switch or locate the poor connection between it and the relay.

If the compressor runs but air doesnt start to cool, then you have lost gas, -dont run the compressor any more.

If shorting the LP switch makes no difference, then swap the relay. If this makes no difference then the ECU isnt grounding the coil of the relay, inwhich case check for fault codes and it being in LOS mode.

What year of Astra is this anyhow?

Tim.