Air Con: 850: Compressor cycling

[Cookeh]

Now that it is starting to get warmer I'd quite like to sort the AC in my 850. My compressor clutch keeps engaging then disengaging, starting immediately upon the AC being switched on.

I measured the clutch gap and found it was 0.8mm, I've shimmed it to 0.3mm now, which I believe is now well within spec. Unfortunately, it still cycles. I know it could be low on refrigerant which will cause cycling, but the last AC place I took it to found no leaks and it was refilled about 9 months ago.

Any other ideas/points to check?

[ITSv40]

Don't rule out low refrigerant, just because the leak cannot be traced. 'er indoors had a Mk 4 Fiesta from nearly new and it had a very small leak for the whole of it's life - 17 years. The aircon was serviced annually, but every year the refrigerant was low. The air-con folks tried every test possible to trace the leak but never did find it.

[Luxobarge]

It's supposed to cycle - about once every 10 seconds or so, although this can vary. The fact that the compressor is engaging shows that it's got gas in it, it might not be the exact correct amount, but it's not low enough to trigger the low pressure safety switch.

If it's cycling VERY frequently, then this might indicate that it's not got quite enough gas, so a re-gas will almost certainly sort it. Get them to refill it with a gas that includes UV dye, that way if it's got a tiny leak somewhere they can find it by using UV light and a detector.

[Cookeh]

It cycles on for one second and off for 3 seconds. Definitely not cycling in a normal manner. I've also read the the pressure sensors could be causing excessive cycling - is this the case, and is there a way of testing them?

I'll try giving it a re-gas as well.

[Luxobarge]

Originally Posted by Cookeh

It cycles on for one second and off for 3 seconds. Definitely not cycling in a normal manner. I've also read the the pressure sensors could be causing excessive cycling - is this the case, and is there a way of testing them?

I'll try giving it a re-gas as well.

Classic symptoms of being a bit low on gas, I'll give you 100 to 1 that a re-gas will sort it and there's nothing wrong with the sensors. Do go with the UV dye idea though, so you can spot tiny leaks, you won't have a hope otherwise.