This summer, my A/C had started running intermittently. It would blow cold air for about ten minutes, then stop. After turning it off for a while, I could turn it back on and it would blow cold for about another 10 minutes or so.
I came on here for some research and found these two threads.
A/C compressor clutch
AC Runs Intermittently 04 Forester
First, I would like to give a big thanks to all the contributors in these threads. After reading through these threads I found that it's common for the AC clutch to wear out over time, causing the gap to become too large. This gap can be tightened up by removing a shim between the compressor and clutch.
I then went out to rent the tools mentioned in the threads, but it turns out my local Autozone does not stock them and it would be a two day wait. I then thought of making my own tool as mentioned. But after looking at the AC compressor. I found a way to perform this procedure WITHOUT any special tools.
All the tools needed to perform this:
3 5mx40 bolts (thread pitch .8)
1 6mx40 bolt (thread pitch 1.00)
A bunch of 6mm washers
Needle nose pliers
10mm Socket with 1/4in ratchet
Ratcheting 8mm and 10mm wrench (doesn't have to be ratcheting, but makes the process much quicker.)
First, I would recommend removing the coolant overflow as it will give you much more room to work. Just remove the two 10mm bolts on the top of it and pull out the line and it comes right out.
Next, thread two of the 5mx40 bolts into the threaded holes in the clutch. Take your 1/4in ratchet with 10mm socket and place it on the bolt head in the center that holds the clutch on. Now, wedge a screwdriver between the 5mx40 bolts and the ratchet. You can now work the screwdriver and ratchet against each other to hold the clutch in place while you crack the clutch bolt loose. See picture below.
There is not much torque on that bolt so the 1/4in ratchet is plenty to take it off. Now, take the center bolt completely out, and work in the third 5mx40 bolt into the last threaded hole on the clutch. This is where the ratcheting wrench comes in handy, as there isn't much room to get a ratchet and socket on these bolts with the radiator fans right there. Take your 8mm wrench and slowly tighten each 5mx40 bolt, you will see how they slowly pull the clutch off.
Do this process slowly as you want the clutch to come off straight. So be sure to alternate from bolt to bolt on a regular basis. Once the clutch is far enough off you will be able to pull it off by hand.
Now that it is off, take your needle nose pliers and remove one of the shims located in the shaft of the clutch that you just removed. It's a very thin washer.
Once this is done, you will want to remove the 3 5mx40 bolts that are threaded into the clutch, and place the clutch back onto the compressor. You will feel it snap into place as it is magnetized, however, it will still be very far away from the compressor. This is when you take the 6mx40 bolt and load it up with some washers to drive the clutch back in, using the center hole where the 10mm bolt holds it in place.
I was able to hold the clutch still with my free hand as I drove the bolt in to suck the clutch back on. Once you get it pretty close, remove this bolt and use the 10mm that was originally there to finish it off. I torqued it back down using the same method to break the bolt loose in the first place. It doesn't need a ton of torque as it is a small bolt, so tightening it by hand with the 1/4in ratchet is plenty.
All in all this process took about 45 minutes, but I am rather experienced with wrenching on cars. Anyone can perform this. It only costs about 4 dollars of bolts and washers. Hope this write-up helps, and will save people a trip to the auto parts store for tool rental.
I should also mention that my ac blows cold nonstop now. Pretty amazing how reducing the gap by that little made such a huge difference.