[V6-12v] A/C compressor R&R

[Tom Christiansen]

Folks,

I was warned that replacing the A/C compressor and associated parts would 
take 10 hours. I was skeptical.

Here are the parts that need replacement:
* Compressor
* Receiver/drier
* Restrictor valve
* Assorted o-rings

In my case, I also had to transplant the clutch from the old compressor to 
the used replacement I was swapping in there. Swapping the clutch is pretty 
easy, but requires three special tools. Thankfully, if you have the Bentley 
manual, the ability to use your imagination, and mechanical aptitude you 
won't have any trouble making the tools yourself.

I enlisted the help of a friend of mine. He took care of the 
receiver/drier, restrictor valve, while I worked on getting the compressor 
out. Everything is pretty straight forward - mostly accessible from underneath.

WEAR EYE PROTECTION!

0) Before you begin have the system evacuated by a professional shop.
1) Remove belly pan, engine top cover, radiator fans, accessory belt cover.
2) Remove oil filter (you can do this without draining the oil in the oil pan).
3) Clamp off the coolant lines to the oil cooler.
4) Remove oil cooler (pulling it off to the side won't give you enough room).
5) Disconnect the compressor speed sensor and clutch connector. The two 
green connectors are hiding in the harness by the radiator fan resistor 
pack. Pull the wires back so they can dangle in your face while you try to 
get the compressor out.
6) Remove three of the four bolts holding the compressor. Loosen the fourth 
bolt (the one that has a nut on it). The bolts are made of steel and 
threaded into an aluminum bracket. Thus, they will take some amount of 
effort and/or penetrating oil to brake free.
7) Disconnect the A/C lines from the compressor (sounds MUCH easier than it 
is). A regular box end wrench fits but you can only turn the flare nuts 
about 1/16 of a turn at a time.
8) Remove the last bolt from the compressor and pull the compressor 
forward, lift up. You'll spill an undisclosed amount of oil on your garage 
floor getting the compressor out...
9) Install is reverse of removal... ;-) Replace all o-rings you've taken 
out. Keep everything clean and coat the new o-rings with PAG 46 oil. 
Remember that the new compressor should have 250 ml (+/-20 ml) of PAG 46 
oil in it when it's installed. If you can't get all the oil into the 
compressor prior to install, you can add at the supply hose (accessible 
from the top) later.
10) Turn the compressor at least 10 turns by hand before recharging with 
refrigerant.
11) Remember to add engine oil and coolant.

I didn't handle the R&R of the receiver/drier and restrictor valve. But I 
didn't hear any significant amount of grumbling from my friend who handled 
that part of the job. The restrictor is located in the supply line to the 
evaporator by the firewall. There's one bolt holding the bracket with the 
two lines. Remove this bolt and pull the restrictor out with a pair of 
needle nose pliers.

The receiver/drier is held in place by two large hose clamps. Just undo the 
connections, open up the clamps all the way, and replace the receiver/drier 
canister.

Even though I had the system evacuated, there was still a bit of pressure 
in there. Probably not much, but enough to give a puff and spatter some oil 
when the receiver/drier was disconnected. Wear eye protection!!!!

The flare nuts are 30 mm and 32 mm. Most of them take 40 Nm of torque, but 
I wish you the best of luck getting a torque wrench on there... The bolt 
holding the two lines to the firewall connection takes 15 Nm. The 
compressor bolts 25 Nm.

Including two tool runs, one parts run, lunch, coffee break, tool clean-up 
we spent 9 hours on the job. I'd guess 5-6 of those were actual work. If 
you are by yourself and have all the parts, tools, I'd set aside 10 hours 
for the job.

Now I just need to get the system charged...

Tom