A/C Compressor Shim Fix: Bread Clip

Let’s talk A/C Compressor Shim Fix

Gatekeeper21 » 

So, I am fairly sure my car is having an issue with the compressor disengaging and then not re-engaging when it should. I am not sure if anyone else has heard about the bread clip shim fix, but I am planning to try that this weekend. My main question, what tool would I use to measure the clutch gap? I have seen that the correct gap should be around .3 -.4 mm. I don’t have anything to measure that and was just wondering what I would need to pick up. Would a spark plug gap tool work or do I need something else?

C@lvin » 

When if starts blowing warm air, does it continue to do that until you shut it off or shut the car off for a while and then it blows cold again when you start it up for a little while and the turns warm again? I am not an expert but if you read up on the clutch gap issue that is a classic symptom.

Two things you can easily check. Just for grins, check your cabin temp sensors to be sure they are clear of lint and dust. They are located next to each grip handle above each front door. You can blow them out with a can of compressed air but be careful because they are a somewhat delicate. If these are clogged it can contribute to difficulty regulating the temperature.

Second thing is you can check your compressor’s clutch gap to make sure it is within spec. The clutch gap should be .3mm. If it is greater than .5mm it is out of spec. and will result in the above mentioned “classic symptoms”.

jimmy57 » 

The compressor relay in the engine compartment fuse/relay box can do that as can the ECC control unit.
The ambient temp sensor next to blower on case could fool the ECC into thinking it is below the compressor cut in temp. but this would likely give other abnormal behaviors besides just a/c compressor.
The engine control unit has authority over compressor and ECT sensor problems can cause the ECM to interrupt compressor relay operation and thus compressor. ANy codes for ECT sensor or other driveability problems?
Last, the compressor has an overtemp switch for compressor circuit on the back of compressor. If this was bad in some way it might complete the circuit when the compressor body warms up from engine temp.

IF it is the relay you could probably start the car and tap on the compressor relay and the compressor would click on.
ECC control unit problems are probably best resolved by elimination of the other items.
Overtemp switch can (and should anyway) be taken out of circuit by unplugging the wires on side of compressor and plugging the feed wire directly into clutch wire with the overtemp switch wires left disconnected. On some the wiring connectors do not allow this but I think it works on that year 900.

C@lvin » 

The bread clip fix worked great on my 00 V70 for the last three years but the symptoms recently returned. The gap measured .3mm after the initial fix and was now at .5mm. I removed the old clips and measured the gap at about .9mm and decided to use some sheet metal I had from Home Depot (approximately .6mm thick) to bring the gap back to near the optimum .3mm width.

I thought the old clips might have become worn or warped, but after looking at them it seems more likely that either the rubber spacers or the internal components have become worn so that a thicker shim is necessary.

This is a quick and easy job and does not require special tools or loosening or removal of the compressor or releasing/refilling refrigerant. If you have a pre-99 compressor it will look a little different than mine (like the previously referenced picture on Volvospeed) but the fix is nearly identical.

When the gap becomes too wide the magnetic clutch will not re-engage. Eventually, it will not engage at all. In order to narrow the gap to within the .3mm spec, you will either need to remove some of the manufacturer’s internal shims or add external shims. Thus the “bread clip” fix was invented by some enterprising DIY individual.

By placing the shims under the rubber spacers that are part of the hub, the springs then push the clutch plate closer to the pulley, thereby narrowing the “clutch gap”.

1. Place the car on ramps or otherwise devise a SAFE way to get under the front passenger-side bumper. Then remove the air guide (AKA air dam, gravel guard, etc.). It is held by two bolts – one on each side. It’s the large plastic part that covers the front underside of the engine and the radiator.

2. Measure the clutch gap. If you are having the classic symptoms it will likely be .5mm or greater. Classic symptoms are that the AC works great for a few minutes and then blows hot air until you turn it off or turn the engine off for a while. The same thing happens each time you start the car. It may begin as an intermittent problem but gradually gets worse until finally the AC won’t come on at all.

3. Decide the appropriate thickness of flat plastic or metal material that will bring the gap back to .3mm. Bread bag clips are popular. I originally used pieces cut from a plastic “For Sale” sign. This time I used sheet metal. Whatever material you use needs to be easy to cut to the desired shape and size.

5. Use a screw driver or other similar implement to place in the space labeled “A” to pry the plate away from the rubber spacer and hub so that you can slide the shim in. You will need three shims. After placing a shim you can just twirl the plate around with your hand to the next spring/spacer. Placing the third shim may be more difficult than the first two because you have removed a lot of the play in the clutch but it is quite doable.

6. Some people put a dab of super glue under the shim. On the post 99 compressor, my opinion is that this is not necessary. On this compressor if you create a large enough shim, the spring will serve to prevent the shim from sliding out from under the rubber spacer. If I recall the pre-99 compressor correctly, it does not provide anything to “hold” the shim like this so super glue may be beneficial in that application.

7. Measure the gap and test the shim before putting the air guide back on. If you turn the air on the plate should engage and spin with the pully. If you turn it off the plate should stop spinning. Take a test drive long enough to assure you that the AC is now working as it should, cycling on and off when it should.

8. Replace the air guide and you’re done. 

2000 S70 – Question about A/C compressor shim fix