I've traced my A/C problem down to this specific problem. I can start the car and drive around all day with no problems with the A/C unless I make a hard acceleration. The ECM is suppose to cut the compressor clutch control off when the car has a hard acceleration but mine does not come back on.

So, I'm driving around nice and cold, then I decide to pass a car or put my foot in it for any reason and my A/C cuts off and the compressor does NOT come back on. Now I can pull over, pump the front of the compressor (with a broom stick) to push the clutch in and the compressor will turn back on. About 5 seconds later the fan cuts on, and the A/C runs fine again until I accelerate hard again.

Does this mean my compressor clutch is bad and needs re-shimmed, a bad A/C relay or do I have another problem?

Another symptom: After driving around for a while, nice and cool. Then I make a quick stop at the post office or somewhere that I turn the car off for less than 10 minutes. When I get back in, the AC will not come back on.

 

Compressor needs to be re-shimmed.

 

In the meanwhile, before you kickdown, turn the ac button to off instead of aut...you can leave the blower on but make it a habit to press the button, then kickdown.

 

Hmmm... Well I'm inclined to agree w/Henry but I still don't understand how pushing the compressor clutch back into the engaged position would also start the engine fan; if the compressor clutch was getting pwr then the fan should have been on regardless of the clutch position. Unless the wiring is not per the schematic, i'm confused..

Any codes by chance?

 

You need to re- shim the compressor. The fan isn't supposed to switch on immediately. It switches on when the high side pressure goes past a set point. While driving on the freeway, in fact, the fan probably never comes on, because enough air is blowing over the condenser to cool it effectively, keeping the high side pressure low enough. Incidentally, the exact same problem just started happening today on my S70. We were driving back from Pittsburgh, and every time I'd accelerate briskly (loving the extra boost from the T5 computer!) the A/C wouldn't switch back on right away after letting off the throttle- it took anywhere from 5 to 10 seconds. This is the first indicator of the air gap getting too big on the compressor. It progresses to "not switching back on at all unless you switch the AC off for a few seconds" to finally "only working when you push the clutch plate in with something."

 

So, I was reading the re-shim instructions that Tech posted and it looked like he was saying to remove the washers. I think I should be adding a few washers, correct?

 

Ok, here is the post that has the clutch reshiming instructions:
https://volvoforums.com/forum/volvo-...shimming-6665/

He said to take washers/shims out to make it a little thinner. If this is the case, something else is wearing somewhere else to cause me to need a thinner shim to close the gap.

Is the gap he is referring to the gap between the clutch plate and the compressor as I look down on it while it's installed? Can I measure the gap now with everything installed?

 

It really would be nice if that works for now. I would rather do a few other things before I tear that A/C compressor apart, especially in this heat. I almost lost 20 lbs Friday when I did my PCV replacement. I cleaned up & painted several parts on the motor while I was at it. It got up to 104 with a 112 heat index.

 

That's the clearance between the clutch plates.

Yes, to insure that that's the problem.

 

You need to remove washers. The gap between the clutch plate and the pulley is what you need to make smaller. Don't take all the washers out- the clutch plate will tend to rub against the pulley when the A/C is off, making a loud racket and eventually wearing the plate further. The washers basically extend the compressor input shaft length, so the clutch plate sticks out further from the pulley. Removing shims shortens that distance and brings the plate closer to the pulley. The best way to do it is to remove the thinnest washer, and see what the gap is. We're dealing with tiny differences here- tenths of a millimeter between "too close so it rubs under certain conditions" and "too far so it doesn't engage." This is why Volvo offers the washers in different thicknesses.

Note that this problem doesn't just affect Volvos. Pretty much every car that has a compressor made by Zexel is prone to this. Kind of sucks, because otherwise, Zexel compressors are some of the best.

 

I read all 5 pages of the "AC Compressor Shim" thread. It appears that some have figured out a way to get the clutch off of the compressor without removing the compressor or depleating the system.
Volvo AC Pump Shim

I'm still a little confused on the process with the compressor installed but it looks like the link was for an S70 which may work for the 850.

As for the trash bag plastic tie Jerry Rig, I'm not sure where they were talking about installing the ties. I am up for trying to do the job on my back with everything still connected. Just need a pair of eye protectors to keep the dirt out of my eyes. I'll read it a few more times, sleep on it, and maybe do it later in the week.

I'll measure the gap tomorrow and post back.

 

Where does one get these 5mm bolts?

 

I got a Puller kit many years ago which does steering wheels, compressors, etc. I think I have seen them at Advance. You could also order it online.

 

5mm bolts are a little hard to find, but I've gotten them from Lowe's before, and even Advance Auto Parts has them. Fastenal would have them too.

 

@#%$&

 

@058ovloV, that is pure sick!!! My mistake on the trash bag tie thing. Because I seen no photos I didn't know what they were really talking about. But this zip tie deal is incredible. I love it. I have about 50 of those things all different sizes. I WILL be using black ones. OMG. It looks like someone could yes 6 of the things and be just as balanced or maybe a little safer than 3. This is pure evolution, going from replacing the compressor, to replacing the clutch, to removing the compressor and repairing the clutch by removing shims, to take it loose without purging the system - pulling the clutch and removing the shims. Now this, just toss a few 15 cent zip ties on there and keep rolling. Pure sick!!!

@Carrots, I did find the 5mm screws at a specialty hardware store. Seem small to me. I'll likely do the quick zip tie fix and maybe pull the compressor apart later.

 

@#%$&

 

Just measured my gap. It's about 0.965mm. Plan on installing the zip ties tomorrow.

 

Ok, I did the zip tie fix. I think I would have been better off and maybe easier to pull the front of the compressor off and remove the shims. LOL It was not easy, how did they do that anyway.

I first installed a big one and it took all of the space, not gap left. So I went one size smaller and it works. Left between .3 and .6 gap. It was hard doing it from up top. Took me about 2 hours to get it done. What finally worked for me was:

1. Pressing a thin flap tip screw driver into the faceplate where the zip tie needs to go.
2. Thread the zip tie through.
3. Pull it most of the way through.
4. Remove the screw driver.
5. Connect the zip tie.
6. Measure the gap.
7. Tighten the zip tie.
8. Do steps 1 - 7 two more times.

Hasn't missed a beat since. Nice and cold.

 

If you gotta, don't worry about opening and recharging the system. Just go ahead and use Enviro-Safe.