S80: Information Aircon has a mind of its own.

[Semnoz]

Originally Posted by Vol S80 Lux

.

Ok so Iv looked under the bonnet at, what I think is the compressor clutch. Is it the pulley directly beneath the alternator?

Its spinning perfectly fine when cold and hot. Unless thats not it.

You can just see the top of the A/C compressor clutch in the photo below. If you're looking at the side of the engine with the wheel-arch cover removed, it's the lowest of all the belt-driven pulleys.

It's driven by a dedicated stretch belt from the pulley directly next to it. This is a short belt that only goes between those 2 pulleys.
This belt, and both pulleys are constantly spinning when the engine is running. The A/C switch in the car activates/deactivates the clutch electromagnet, which in turn causes the pulley to bind to the A/C pump drive-shaft.

[Vol S80 Lux]

Originally Posted by Semnoz

You can just see the top of the A/C compressor clutch in the photo below. If you're looking at the side of the engine with the wheel-arch cover removed, it's the lowest of all the belt-driven pulleys.

It's driven by a dedicated stretch belt from the pulley directly next to it. This is a short belt that only goes between those 2 pulleys.
This belt, and both pulleys are constantly spinning when the engine is running. The A/C switch in the car activates/deactivates the clutch electromagnet, which in turn causes the pulley to bind to the A/C pump drive-shaft.

I see. So what Iv been looking at isnt the air con compressor but something else.
I read on another forum that to access the air con compressor you need to remove the front wheel arch cover.

My concern is that I have a leak in the system somewhere because today at even 18 degrees with the aircon switched on, the air is still mild. Not like an aircon should be or how it was 4-5 weeks ago.

Are there any leak prone areas on this car I could quickly check or replace.

Removed pollen filter today but cant get another one till tomorrow

[Laird Scooby]

It was cooler a few weeks ago. As the ambient temperature goes up, so does the gas pressure inside the A/C system. If you recently had it recharged, they may have added enough gas to get you near the top pressure limit on a cold day.

Now it's a lot warmer (even at 18C it's warmer than a few weeks back) it's probable the high pressure switch is cutting the A/C out to prevent damage to the compressor. Wait until it gets a bit cooler still then try it again or take it to somewhere that does A/C and get them to put the gauges on so they can see what's happening.
Guesswork isn't a good thing with something like air-con!

[Vol S80 Lux]

Originally Posted by Laird Scooby

It was cooler a few weeks ago. As the ambient temperature goes up, so does the gas pressure inside the A/C system. If you recently had it recharged, they may have added enough gas to get you near the top pressure limit on a cold day.

Now it's a lot warmer (even at 18C it's warmer than a few weeks back) it's probable the high pressure switch is cutting the A/C out to prevent damage to the compressor. Wait until it gets a bit cooler still then try it again or take it to somewhere that does A/C and get them to put the gauges on so they can see what's happening.
Guesswork isn't a good thing with something like air-con!

Well I certainly wont be going to autocentre again.

[Laird Scooby]

ATS Autocentre by any chance?

[Vol S80 Lux]

Originally Posted by Laird Scooby

ATS Autocentre by any chance?

Autocentre in Dewsbury.


Spoke to an air con specialist and explained the situation.
He lives about 10 miles away from my work place.

He said he could find the leak using nitrogen. Thats different to the dye most other places use and he could find it within 30 mins or so for a donation of 30 pounds.

Repair the leak and regas for another 30 pounds.

Can nitrogen be used to locate a leak? Or does it sound 'too good to be true'.

[Laird Scooby]

Different autocentre to what i thought then.

I see now reason why nitrogen can't be used to find air-con leaks, it's an inert gas and the atmosphere is full of it already (about 79-80% nitrogen in the air we breathe!) so won't matter if large quantities leak out.

It sounds like a very good price but not too good to be true (equates to £60/hr) to find any leaks, fix them, vacuum the system down and regas/test. It is presumably plus any parts used though which may well carry a premium in terms of cost.

Ask him if he guarantees his work in writing - if he says yes then go for it!

[Vol S80 Lux]

UPDATE.

I have a friend who works for VW. Explained the problem to him. He offered to use his uv blue light to find the leak.
Under the bonnet, everything looked fine but where the pollen filter is and further up; so behind the glovebox we saw the dye shine up green. Also saw a lot of traces of dye inside the glovebox but the pattern of the dye looks as though its been splattered from somewhere else.

Couldnt locate the evaporator but his diagnosis was that it must be the evaporator thats leaking.

I think its a big job and too expensive so Im leaving it for now but I might take the glove box out just to be nosey and see if I can find more traces of the dye.

[Laird Scooby]

Sounds like you need to remove the glovebox then!. If you follow the two air-con pipes to where they go through the bulkhead to the heater box, you'll know roughly where the evaporator is. The pollen filter should (in theory at least) be before the evaporator so the evaporator doesn't get blocked.

It's about £100-150 for a new evaporator for yours, depending which one exactly you've got :

https://www.ebay.co.uk/sch/i.html?_f...rator&_sacat=0

Once you've located it there's no reason why you shouldn't do the job yourself if you do most other things yourself. Just remember to get the system recovered before you start so that firstly you don't let all those CFCs loose into the atmosphere, secondly you don't get frostbite from the escaping gas and thirdly so that while you're having a crafty fag while doing the job, it doesn't react with the R134a and give you cyanide poisoning!

Should be a "spanner job" to change it once you've worked out where it is and how to get at it. After that you'll have to get the system evacuated and then refilled with fresh oil gas and if you wish, leak detector and a sealer.
Don't forget to clean off the "Slimer spots" of UV dye so that if it does leak in the future you won't be looking at old spots and confusing them with new ones!

[Vol S80 Lux]

I think you're right.

Are there any instructions/guides online to help me get to the evaporator?

Hope there is because Id like to have a go at this myself.