A/C Update Kit
Living in Texas, summers can see 100 degrees. Being I have a black car with black interior, summers are unbearable in the Porsche. I felt that working a/c was high priority on my list of things to do to the car. My 951 was bought without any working a/c. I chased the problem to a faulty clutch solenoid. Since clutch solenoids are more than $150, and I had no idea if the compressor would be bad or leak when spending money on the clutch solenoid, I felt that it was best just to replace the whole compressor.
My next decision was which refrigerant I would use. R-12 is the original refrigerant. Many people claim that it blows cooler, but with a single can of R-12 running more than $30, combined with the fact you have to have a licence to buy it, I thought R-134a would be a better choice. R-134a can be bought at any auto parts store. I felt this was good because with a 20 year old car, you could have a/c leaks. I could refill the system, at home, whenever I wanted. I could even re-fill the car on the road with a small charge hose (I carry one in all my older cars).
Since I decided to run R-134a, I then needed to decide which compressor to use. The two options are to buy a remanufactured stock Nippondenso compressor which was originally intended to run R-12, or buy a new compressor designed to run with R-134a. I thought it would be best to use a compressor originally intended to run R-134a.
The kit I used is the kit sold by 944 Online seen here. It comes with a new Sanden compressor, new drier/receiver, a length of hose, and adapters to use the mounting system used by the Sanden. The directions that come with the kit are very vague, and a real a/c novice may not be able to figure out exactly what to do. Thus, I have written the following procedure for the kit.
To install the kit, you need to modify the new compressor, and cut your suction and discharge hose.
Removal of Compressor per Porsche Service Manual
Drain air-conditioning system. If you have R-12 in your system, you need to let a professional excavate it, as it is illegal to discharge R-12 to the atmosphere. If you have an R-134a system, you can just bleed it off the service port to the atmosphere.
Disconnect Loosen both lock nuts on the a/c compressor adjustment strut.
Remove the V-Belt. A new belt comes with the kit.
Remove the bolt on the a/c compressor adjustment strut that attaches to the compressor.
Disconnect the electrical plug for the compressor.
Remove the suction and discharge lines from the compressor. Be prepared for refrigerant to blow out of the hose connections, make sure you are wearing safety glasses, and keep your face away from the hoses.
Inspect New Kit
The new kit will come with most everything you need. Make sure that you have everything. There is a material list in the instructions, make sure you have everything.
My kit did not come with o-rings. You will need to put o-rings on the barbed 90* fittings on the compressor as well as put new o-rings in when you install the receiver/drier. So, go to your auto parts store and buy some. I just bought a variety pack of o-rings. Make sure you buy green o-rings.
My kit also did not come with enough of the special a/c clamps. The clamps have a spacer bar that you fit at the edge of the hose. This ensures that the hose clamp is set at the correct place on the barbed fitting. You can use a regular hose clamp on the suction side of the compressor, as it only operates at around 100 psi.
Preparing the New Compressor and Hoses
The new compressor will not fit in the stock location, as one of the mounting ears will hit your oil pan. This mounting ear is not used, so it needs to be ground off. You will also need to replace the electrical terminal on the new compressor to a spade type terminal.
I used a sawzall to cut the majority of the ear off, then went back with an angle grinder to smooth it out. Use a new grinding disk and throw it away when done. Aluminum is very fine and can clog up the grinding disk, this can potentially make your grinding disk fall apart if you use it again on mild steel. After you finish grinding, use compressed air to blow all the aluminum dust off the compressor, concentrate on the clutch area the most.
Since the new compressor uses a barbed fitting and the old compressor uses a fitting that mounts to the compressor, you will need to cut the old fitting off the suction line.
Cut the fitting off as close as possible to the old fitting. Make sure you cut it straight. I used a small hack saw and used the old crimp as a guide. This open hose will be clamped on the 90* barbed fitting on the compressor.
Find the line that goes from the compressor to the condenser. It attaches to the condenser, then makes a 90* turn towards the engine compartment, then another 90* turn going back towards the compressor. I left it bolted the the chassis to help support the line while I cut.
You will need to cut this line. Make sure you cut it as straight as possible. You may also need to support the line with one hand while you cut with the other hand. This is line is thin and delicate, and you don't want to bend it. When you finish cutting the line, remove the bolt that attaches it to the chassis and throw away the old hose.
Install the compression fitting on the old line. Tighten it as tight as possible, as this side of the compressor operates at very high pressures. I found that having a friend support the line while I compress the fitting with two wrenches much easier. Once again, this line bends super easy so be careful.
Installing New Compressor
First attach the bracket to the stock locations. Use the diagram that came with the kit to see the proper orientation of hardware. You will need to use a spacer bar on one of the mounting locations. Two spacer bars and bolt sizes are given. I do not know what models need which spacer. So just see what size bolt you need, and use the appropriate spacer. Only lightly install these bolts, as you need to let them pivot to orient the compressor in the right place until you tighten the adjustment strut.
Mount the compressor to the compressor mounts. I mounted the bottom ones first, as it was easier to align it on those first. Tighten them down tight.
Rotate the compressor up and install the rest of the bolts. Tighten them down tight.
Put the belt on, but only loosely (let it hang). This is to get the compressor orientated close to where it will actually be once tightened down properly while you fit the hoses.
Fitting New Hoses
Push the 90* barbed fitting into the hose. It will take quite a bit of muscle. It's a good idea to lubricate the fitting with new ester oil. Once the fitting is put inside the hose, install the fitting to the compressor. Make sure the hose clamp is in the proper location. If you use a a/c style hose clamp, the spacer bar needs to be at the end of the hose. If you use a regular hose clamp, guesstimate the exact location as if it were to have a spacer bar on the hose.
Your kit comes with a length of a/c hose. This totally replaces your old discharge line. Push one end of the a/c hose onto the compression fitting at the condenser side. Make sure the a/c hose clamp is in the right position by using the spacer bar.
Install the 90* fitting loosely on the compressor. Then, take the other side of the hose and locate locate it near the fitting. You will probably have to cut it to length (I cut about 8" off). This part of the car is not very tight on space, so you can be a couple inches off. After you cut the hose, push the hose into the 90* fitting. Once again, make sure the a/c hose clamp is in the correct position.
Install the belt properly, make sure all of the bolts on the compressor mount and 90* fittings are secure, and double check to make sure the hose clamps are tight.
Install the Receiver/Drier
Install the receiver drier is simple. Loosen the receiver/drier clamp. Remove the a/c lines from both side. Install new receiver/drier (make sure the orientation is correct, there is a flow arrow on the receiver/drier). Install new o-rings on a/c lines and tighten lines to receiver/drier. Tighten the support clamp for the receiver/drier.
Filling A/C System
COMING SOON WHEN CAR RUNS!
If you don't want to fill the system yourself, you could always drive to any automotive repair facility and have them do it. Filling the system yourself requires about $100 worth of specialty tools. An automotive repair facility will probably fill your system somewhere between $100 - $200. The choice is yours.
I will update this page once my car is actually running and I can fill the system.
Enjoy your a/c!
Shameless Plug
If you find this information helpful as a book you would have had to buy or a service you would have had to pay for, feel free to help me write more with a donation.
Thanks, Blake.
