Air Con: Air con not working

[El Padrino]

My air con hasn't worked since owning my 98 V70R for the past two and a half years. I've had it listed as a low priority fix until the rest of the car had her urgent issues addressed first. It'll be a very 'nice to have' if the air con can be fixed and working.

I looked at the ac compressor clutch and can see the previous owner(s) have put three zip ties in place to decrease the gap size. Using a 0.3mm feeler gauge (the minimum gap), the gap is correct, so I didn't add further zip ties. When I turn the ac clutch by hand, it is turning. The fan and ac lights all work fine, but the ac clutch is not engaging with the engine on and up to temperature, when the ac button is pressed.

I've not had any leaks or the ac gas level checked, so I don't know if there are issues there. So, a few questions:

1. Does the air con need gas in the system in order to engage the ac clutch?
2. Is there a simple way to check if the ac clutch is in working order without dismantling it etc? I'm prepared to do any checks if provided with a simple and methodical approach, preferably with photos and arrows pointing to which parts etc

Many thanks in advance if you have any tips.

[Tannaton]

- There is a pressure switch in the system on one of the pipes, if the pressure is low (i.e. low or no gas) the a/c clutch is disabled but with no warning light etc.

- The a/c clutch is a simple 12v coil, you can test it by applying +12v to the single wire to it (it earths through the engine block usually) and see if it moves. You can also apply +12v with the engine running to see if it turns but only do that for brief periods in case the oil is low (it is also the lubricant for the pump). If you have a multimeter you can also check if the a/c clutch is getting power with the engine on and a/c enabled.

[El Padrino]

Originally Posted by Tannaton

- There is a pressure switch in the system on one of the pipes, if the pressure is low (i.e. low or no gas) the a/c clutch is disabled but with no warning light etc.

- The a/c clutch is a simple 12v coil, you can test it by applying +12v to the single wire to it (it earths through the engine block usually) and see if it moves. You can also apply +12v with the engine running to see if it turns but only do that for brief periods in case the oil is low (it is also the lubricant for the pump). If you have a multimeter you can also check if the a/c clutch is getting power with the engine on and a/c enabled.

Thank you Tannaton for those tips. I'll need to find a good video on how to do that if there is one.

[Luxobarge]

As per Tannaton's post, almost certainly low on gas. I'd strongly recommend getting it re-gassed first, very unlikely to be a clutch fault, and if it's not been working for that long then VERY likely to be low gas. Save yourself a lot of faffing and get it filled, drive home in nice ice-cold air.

[ITSv40]

Agree with the above two posts. Most likely cause of it not working is low or non existent gas. Get it tested and filled and go from there.

[El Padrino]

Thanks ITSv40 and Luxobarge, I'll have the system re-gassed and go from there. I hope that's all it requires.

[V70Zig]

Don't know where in the world you live, but KwikFit offer a free aircon check.

[Luxobarge]

Originally Posted by V70Zig

Don't know where in the world you live, but KwikFit offer a free aircon check.

For what it's worth, I wouldn't trust KwikFit further than I could spit them. They can't do much to "check" the aircon system without refilling it, free or not. I've heard too many stories of goons filling it with the wrong gas or wrong quantity, not putting in the oil etc. - avoid, IMHO.

[V70Zig]

Originally Posted by Luxobarge

For what it's worth, I wouldn't trust KwikFit further than I could spit them. They can't do much to "check" the aircon system without refilling it, free or not. I've heard too many stories of goons filling it with the wrong gas or wrong quantity, not putting in the oil etc. - avoid, IMHO.

I agree to disagree, yes there are goons everywhere. How they check it I don't know, it's free and no obligation to have it gassed there. If they vacuum it and it doesn't hold they wont be able to fix it anyway the same goes for many places.

[4x4]

Vacuum testing the A/C system will only fail if the leak is significant enough to show. Small leaks are not detected with a vacuum test. Best method is to have a pressurised nitrogen test as it will show even the smallest of leaks