Air Con: Aircon stops working when hot

[gmonag]

I keep banging on to DIYers about doing a proper diagnosis before swapping parts. So practicing what I preach here is a little story (with ****-ups).

2005 D5 163hp Exec

My aircon began cutting out last summer whilst towing a large caravan around Europe. Weather was HOT (38C), but all worked OK at lower temps. Recently it started cutting out at 25C+.

Possible causes:
Insufficient refrigerant
Faulty controls
Faulty pump/magnetic clutch
Faulty cooling fan

VIDA ac cut out txt.jpg

On a warm day (28C) I hooked up VIDA (no DTCs) and ran the system at idle. I displayed the data on the graph and after 15 minutes the ac cut out. I put a gauge (from a EZI-Chill refill kit) on the low side. It read 26 psi - normal. VIDA displays the high side - again normal. So refrigerant OK. The system was responding to the controls until it cut out, so no problems there. The cooling fan was running and changing speed - OK. You will see from the data that the computer was switching the pump on and off but when the ac stopped workng it did not respond. I checked the magnetic clutch and it was not turning. So I CAREFULLY tapped the clutch plate with a long pry bar and it snapped into place and the ac cooled again. After a few seconds it disengaged and did not re-engage until tapped.

So diagnosis - magnetic clutch gap too wide.

Possible fixes:
Replace pump
Replace magnetic clutch
Adjust gap
Ghetto fix
Proper fix

Pump is working OK and not noisy, so no need to replace.

Volvo quoted £350 for a new clutch assembly + wait for it to come from Sweden! Scandix have a new clutch for €109. Too expensive

Adjust gap using SiRobb's method (Ghetto fix) - His video is on an S60 but the XC90 does not have the same access. Going in through the front RH wheel arch will work though. However if I'm going to do that I may as well do the "proper job" and take out a shim or two from the clutch.

[gmonag]

The ac pump/clutch is easily visible but very difficult to access. It sits right up against the frame.

Disconnect battery
Raise the front of the car and remove front RH wheel
Release and bend back the wheel arch liner.
Remove engine cover
Unclip power steering reservoir and move aside
Release aux belt from ac pump
Release air charge pipe from intercooler and move aside
Disconnect electrical connection to ac pump
Remove engine lower shield
Remove engine crash protector (6 bolts, lift and push forward)

Working inside wheel arch/under car/from above:
Release ac pump (4 bolts). Do not disconnect refrigerant lines.
Move wiring/pipes as required to manoeuvre the pump to gain access to the pulley.
Measure clutch gap using a feeler (spec is 0.4-0.6mm). Mine was 0.95mm.
Remove central pulley bolt
USE PULLER to remove the clutch plate. This is where I cocked-up. I had read on the web that it is possible to pull the plate by screwing 3 M5 bolts evenly into the holes and forcing the plate off. It does not work. Make or buy a puller. I bought this:

https://www.ebay.co.uk/itm/AC-COMPRE...72.m2749.l2649

I managed to damage my clutch plate getting it off using brute foce after I failing with the other method. So I bought a used pump from a breaker for £30 and used the plate from that.

Ensure you recover the 2 or 3 shims (they look like slim washers) from inside the clutch. Measure the thickness of each shim and remove as required to adust the gap.

Plate.jpg

Reassemble and check the gap. Mine was 0.5mm - perfect.

Refit everything and test. Hope that helps you out.

[oragex]

Nice write up. I also had problems removing the plate and even tapping it back in plate. It's tight on the shaft plus the plate is flexible because of the springs. Can indeed be hard or even impossible to pull it from there (on top of the 3 bolt method) without prying it out and bending an edge which is not good news because the plate must stay flat or it will rub against the compressor while it's not spinning.

As for the gap, basically the gap needs to be the smallest possible as long as the clutch doesn't rub against the compressor while not spinning, the smallest the gap, the better. But indeed 1mm is huge and needs immediate attention.

[Maccartw]

Gmonag,

Did this repair today as the air con stopped when hot. Works perfectly. Saw SiRobbs youtube video as well. Great post. Thanks.

[aland]

I've done the repair on a few cars, but always the proper fix by adjusting the shims.
I usually make a puller from scrap steel cut / welded as needed.

[owenfackrell]

I did my shins at the weekend and ended up taking them all out.
I didn’t bother taking the wheel off or the engine under shield as I could reach all 4 bolts from above. I did also take the other bolt out from the alternator and basically needed up swapping the 2 around to give better acces to the clutch plate.
With a proper puller it is actually a very simple job to do and is possible even easier than any of the ghetto fixes on the xc90 due to the very tight access with it in place.