Air Con: 850: 850 air-conditioning fault diagnosis

[Stu B]

Hi All,

I'm after some assistance with this. The car is a '95 850 T5 estate with ECC.
The air conditioning aspect has never worked in my ownership (3 years ish) but otherwise the ECC works properly on 'auto' in terms of controlling fans, directional flaps, heater temperature.

I started investigating yesterday and found I had two fault codes stored against the ECC, they were 4-1-4 and 4-1-7 which related to seized interior temp sensor fans (I didn't even know existed!). I've now cleaned those up, can see them working fine, and reset the codes which haven't come back so the ECC appears free of fault codes at least for now.

Next I looked at the AC compressor as this doesn't kick in, potentially because there is no refrigerant I expect. As an aside, I suspect the evaporator has probably given up and leaked years ago but need to work through each bit to establish that I suppose and if a fix is viable as otherwise I'll be looking to replace the car now I use it to commute daily and want working AC.

The compressor clutch gap when measured with feeler gauges is is around 0.45mm, though noticeably a little tighter in places around it's circumference than others. The centre part rotates freely by hand, but remains stationary with the engine running and the outer pulley turning, so the clutch not engaged. I carefully tested giving it a poke with a piece of wood when running to see if I can reduce the gap slightly and encourage engagement, but I can't - again, likely due to no refrigerant?

I read about jumping the connections to the sensor (pressostat?) on the line by the bulkhead to trick the clutch into engaging for a split second with no refrigerant but didn't want to risk it without more research. I also found what I think is the AC relay under the dash (a blue one) and need to test that too. The 25A fuse in the usual fuse box is fine.

That's about as far as I got, so I could do with some assistance of where to go next if anyone has suitable advice? I suppose the options following that are to try getting it gassed and see where it leaks, assume the evaporator is knackered (see note below) and get on with replacing that, big job and then get it gassed?

* Note: A receipt from 2001 in the service history to diagnose AC failure (when the car was only 6 years old!) pointed to an evaporator leak and 'noisy compressor' hence my thoughts around the evaporator. Compressor wise, 'noisy'? Bearings maybe, but aren't they noisy when the refrigerant is low anyway, I've has a few others that were?

Waffle complete - any help appreciated to make my T5 cooler for summer

Edited to add this link I'd been using yesterday to assist, very detailed!
http://www.volvotips.com/index.php/8...ervice-manual/

Cheers
Stu

[Luxobarge]

In my view you've done all the right things. As you mentioned, next step is to get it re-gassed. Take it to a reputable place that knows aircon properly (i.e. not Halfrauds, Kwikfit etc.) They will remove the existing gas and you will then know how much was in there - I'd put money on there being not a lot. Part of the re-fill process will be a vacuum test, i.e. if it doesn't hold a vacuum then there must be a leak that needs to be fixed before filling. This will usually only detect fairly significant leaks, if there is a smaller leak it won't be immediately obvious. To help with this get them to re-fill it with gas that also has a UV sensitive dye in it, that way they can then scan around all the usual suspects with a UV light and see where it may or may not be leaking. If no leaks immediately detected I'd expect it to start working and blowing cold air - these systems are pretty powerful so you should be in no doubt that it's working. You will also hear "the click of joy" which is the periodic click the compressor makes every time it engages.

If they do detect a leak, get them to replace or fix the leaking component before re-filling if possible, as the gas is quite expensive now, and the cost of multiple re-gassing can mount up. Well worth fixing in my view, I spent a fortune getting my V70 system up to scratch (including a new compressor at one point) but don't regret a penny of it. Use the aircon even when it's not hot weather, because a) it lasts longer if it's used frequently and b) even in cool weather the aircon dries the incoming air and helps A LOT with de-misting.

HTH?

[byootox]

One quick and easy way to see if the evaporator is leaking is to use the electronic sniffer on the vents when the A/C has been gassed and blower fan on.
If it's leaking it will show up pretty quickly.
Plus you will get a bit of a smell coming from it, the PAG oil in the system is smelly stuff and any leaks can cause it to escape.
An evaporator isn't expensive to buy but removing the dash to gain access to it is a bit of a pain.
The one part I find that leaks regular on these cars is the accumulator (it corrodes through) but it's a cheap and easy part to replace.

[Cookeh]

Get it regassed for sure, but the clutch gap itself is still considerably out of spec (0.3mm) which may be why it doesn't engage.

[Stu B]

Cheers, chaps! Very helpful indeed, thank you. It sounds like a re-gas and leak test is the next step then, but yes, as mentioned above - the gas is a lot more expensive now than it used to be so wouldn't want to be doing it too often.

I'll have a search for local AC specialists and see if I can find anyone suitable to gas it up and find any leaks for me. In terms of replacement parts prices, they don't seem too bad so long as you don't have to replace the whole system!

I'll keep you updated and probably have more questions as this progresses. Really hope the AC can be fixed, as I've been looking for a potential replacement car with working AC and preferably an auto for commuting but struggle to find anything I fancy as much as the old square thirsty Volvo

[Paul240480]

I had a similar issue with my old 850, had it 4 years before I got round to A/C.

In my case the clutch wouldn't engage. I 'fixed' that following a guide on Matthews Volvo site. Which involved putting wire behind the three 'spokes' on the clutch to move it closer 'in' . This can be done without removing g the compressor. You can remove and put shims in to move the clutch further 'in'. With my limited skills, I went for the 'wire fix'.

After a gas all was cold for about 2yrs after a regas. Next time I tried a gas, the mec fell about laughing as before he connected it he found a hole the size of a 10p piece in the drier bottle.
These are sold separately , I got one for around 40 quid. Had it fitted and the gassed and all was chilly once more. I sold the car 2yrs ago and it's all still cold with current owner.
The drier bottles are cunningly placed to pick up all the crud the roads can chuck at them and are often the cause of any leak.
Good luck.

[Luxobarge]

As above, when I was aggressively sorting mine, I replaced the drier bottle thing as a matter of course - it looked cruddy, and apparently the system benefits from a new one of these from time to time, so to save wasting gas re-fills I obtained one and got the garage to change it before the last re-fill.

Have a look at yours and unless it looks in really good condition, you may wish to do the same before having it re-gassed?

[Stu B]

Cheers, All - advice noted and the car is booked in with a local AC specialist next week to test for leaks and/or any electrical issues and see what needs doing. Time and weather permitting, I’ll do a bit more checking and troubleshooting at home this weekend first to make sure the AC relay is ok, have a look at the receiver/drier bottle and make sure I’ve no fault codes logged since resetting last week.

I’ll report back with progress

[Stu B]

Update: AC fix hasn’t happened yet, as a). my wife’s car’s clutch and DMF went last weekend so sorting that first (£££!) and, b). I’m potentially replacing the Volvo with something else that already has working AC (and is auto) so it may soon be unfortunately surplus to requirements.

I’ll update once I’ve collected the other car and of course advertise the Volvo on here if I do need to move it onto a new home...

[Stu B]

Quick update to say I collected the other car, seems good so far (not as comfy as Volvo though or as quick I’d say!) so the T5 will be up for sale ASAP. I’ll write an advert later today if I get chance to find it a good home