A/C compressor, rebuild or replace?
 

All,
My 87 Cab A/c system (R12) is FUBR! I knew this when I bought the car & A/C is a MUST in North Texas. I have tried to read & keep up with all the treads on Air Conditioning. My Nippendenso compressor is removed, should I rebuild and convert to R134A or simply replace with New compressor?
I have been assisting a friend with his Factory Five (Type 65) Hot Rod. He has purchased all the tools to fabricate A/C hoses. We have completed his A/C system and all components work properly with no leaks.
I will purchase a complete A/C system or rebuild my current compressor, fabricate my own hoses, purchase evaporator/condenser and upgrades for fans and vents to finish the project.
While cost is always a factor and doing the grunt work is not a problem, I don't want to compromise the system.

Standing by for the blast!

Thanks,

Terry

The rebuild kits for the nippondenso compressors are crap. The seal on the shaft fail after less than a year. Went through this a couple times with me 911 and also the turbo. final fix both times was replace it with a sanden.

I've been asking myself the same question regarding an old Sanden (SD5?) which the PO put on my car year ago. I'm pretty sure I have a leak in the compressor seal since I can see a very faint oil stain on the engine lid. What is odd is that I put a fluorescent dye in the oil but the stain does not show up under a black light...
My a/c is working better than ever but the compressor seems really noisy but it's ALWAYS seemed noisy so it may just be the way it is.
New Sandens are not very expensive so that may be a better option for you.

If the compressor has well under 80K miles on it I'd suggest starting with
tearing it down and inspecting the bores, pistons, wobble plate, reed valves and the shaft. There is a tutorial HERE to get you started. If things look good then you can consider a reseal job.

You can reseal the compressor with the OE style seal system,
provided the compressor is in good condition, and it will hold up, however
if the shaft is corroded or you have system pressure issues then you will
have subsequent issues.

If the compressor has worn pistons, bores, wobble plate, reeds or shaft issues, then its time for a new compressor. I'd suggest sticking with the Nippondenso.

What he said.

what are the chances it is fine as is? I took the denso off my 84 930 recently. My plan was to try to rebuild it. It seems to spin freely and smoothly. I didnt see any oil stains anywhere. I took the clutch off but then thought maybe Ill try to use it as is. I think it might be fine, but I cant really test it out of the AC loop.

You say it spins freely. Are you just spinning the clutch or actually turning the compressor?

It all depends on why the AC system is not working. If you try to use it the worst case is the nose seal is blown out big time and the refrigerant all leaks out. If the compressor is bad you will have to recover the refrigerant and start over. With the proper equipment that is not a major deal.

If your own time and labor are not a major issue, put it back on and pull a vacuum. If it hold for a day add the refrigerant. and give it a shot.

yeah thats my plan, the actual compresser spins freely and creates suction when turned. MY system definately has leaks elsewhere though and hasnt been operational in at least a dozen years. I need to replace the line and bring everything back up to spec before I can test it in-situ.

Is the compressor in question one that originally came with the car or was it replaced or rebuilt at some time?

How many miles do you guess are on the compressor?

definately the original. Less than 30k miles on the whole car. The compressor would have been disengaged for most of those. I will be ording some parts from you guys in the near future :).

The low mileage is a good sign.

You try an use it as is, or ask yourself if you want to
put a seal kit in it and be done with it.

Guys,
Thanks for all thr replies. My nippo has been overhauled by PO, don't how long ago? My car 88,247 miles. The car was in Colorado & New Mexico, PO told they didn't use A/C all that much. The Car is now in north Texas, so A/C is a must for all year driving. I start with seal kit and go from there, thanks again.

Terry

OK...follow on to my prior question. I removed the compressor (Sanden 507 series) from the system but kept the clutch connected so I could activate it with the switch. I can turn the clutch and it seems really smooth...would I have heard anything it it was going out? It just seems kind of noisy when it runs but maybe they all do that. Anyone have experience with this model? I really don't have a problem replacing it since they are not very expensive but I don't want to replace it and find out they are just naturally noisy.
THanks

What are your turning, the outer clutch hub or the pulley?

It all depends upon where the noise is coming from:
1) The AC belt
2) The compressor body
3) Vibration in the mount
4) Clutch pulley assembly
If you overcharge a system you can have some noise in the body of the compressor.
So, before you toss $$$ at a compressor and recharge you will need to pin down where the noise is coming from.

Most A/C components, hose, seals, O-rings, of this era were guaranteed against leakage up to 35 bar, 500 PSI, BURST pressure ~50 bar, 800 PSI. Many factory systems of the time, even those with pressure control sensors, included a 450 PSI vent to atmosphere (yes, R12 even) HPRV, High Pressure Relief Valve to prevent accidental or inadvertent refrigerant over-pressures.

Our Porsche A/C designs seem highly subject to over-pressure if not somehow modified to prevent same.

You should start with a Red DOT trinary switch that opens the compressor clutch at ~350 PSI and use the third element to power the cabin heat blower/fan directly or via the heat controller module.

i switched the compressor on and then turned it so it was actually moving the pistons. Seems to run smoothly as far as I can tell. It was disconnected from the hoses so there was no pressure being generated.

Well, then just leaves the noise issue to explore.

I've never had good luck with rebuilt compressors. I'd go with rebuilt anything else, such as alternators, starters, distributors, etc etc. But my opinion on AC compressors is now that it's going to come back and bite you if you rebuild them. I'd buy a new one unless it's going to be 3 or 4 times more $$.

I can't agree on that, after resealing, literally, 100's of 10P15 compressors over the years.

Most issues, in terms of a nose seal failure, have to do with technique/procedure of replacing the seal: some DIY's insert the seal upside down, some crack the carbon, some install it on shaft that is pitted, some pinch the outer race o-ring in the snap ring groove in the nose. If your system is seeing pressure spikes, is overcharged or you have excessive pressures... it will blow out. On case seal O-rings , some DIY's pinch the o-ring or damage thin aluminum faces on the case halves.

And in this regard "cleanliness" of the workspace, tools, and components/parts is of the utmost importance.