Mattman928

I am planning on replacing all then o rings in my AC system since it is leaking freon.

When I start reassembling do I put the o rings in dry or do I need to lubricate. If lubricate, what do I use for that.

Also the AC hasnt been used for three years, do I need to worry about the compressor? Should I flush it, rebuild it, or just bolt it in and let it rip.

Thanks in advance

Bill Ball

The o-rings can be lubed with the same oil that goes into the compressor - mineral oil for R12 systems.

As to what else to do with the system, that's a judgment call. If you think that the system just losts its Freon due to leaky o-rings, then replacing them, drawing a vacuum and recharging Freon should be all that is needed. Replacing the compressor shaft seal might be a good idea as it may be the source of the leak. A "flush" should only be needed if there was a compressor failure/seizure. New receiver-drier is a must (cheap anyway). Anything beyond replacing the shaft seal on a compressor is not very feasible in terms of a rebuild. Best to buy a new or good rebuilt one in that case. "Cheap" rebuilt ones are available on eBay - I've bought several and not had any work for more than a year or two.

Jadz928

Orings go on oiled, with the large fitting tightened very snug, but not overtight where it compresses the orings too much.
How deep to you want to go? Fix only what is apparently broken, or fix everything (what is just about to break?)
Is the AC comp. original?
Running R12 or converting to R134?
Have you inspected the hoses for leaks?
Replace exp. valve WYAIT?
Receiver/dryer is a must replace
Do you have rear AC?

the flyin' scotsman

I had the similar dilemma:

replaced a/c compressor
replaced both compressor hoses
replaced all Orings
replaced expansion valve
replaced rxr/drier
rebuilt HVAC head with new relay

Result: perfect a/c

blown 87

I always do a flush if I am going to warranty the job, even if there has not been a compressor failure.
The reason for that is that after all these years almost all of them have to much oil in the system, and on top of that most folks have not a clue to what the proper amount of oil is.
Is it a six cylinder compressor? A ten cylinder compressor? What year model? what was the factory fill on it as far as freon?

The early models hold a lot of oil, the late ones hold very little on R-12, but hold several OZ more with 134A, also what was the SSU of the oil in it? What should the SSU be of the oil going into the system?

So IMHO you should replace all the O-Rings, both expansion valves (if it has rear AC) and the drier at the least even if you do not replace the compressor.

My take on it.

Mattman928

Thanks.

The compressor is original. How difficult is the shaft seal replacement? Is it a DIY project??

Thanks

Bill Ball

The seal can be bought and installed yourself, but I gather you've never done this. Well, there's always a first time, but for me that usually involves breaking things and taking forever and then buying a new part in the end. But if you don't mind that possibility, carry on.
I think this is the kit...
https://www.ackits.com/pc/21-34629/N...SHAFT+SEAL+KIT

Greg mentions he flushes, but just know that requires lots of AC flush solvent and some tools. You don't use a garden hose.

dprantl

You need a shaft seal installer to install that shaft seal because it is a lip seal. Also, you need to be REALLY careful when you push the seal on the installer. I think the best way is to push it on the opposite way, then, take it off, turn it around and install it the right way onto the shaft seal installer to properly enlarge the hole in the carbon seal. Then put it into the compressor nose, put the seal installer on the shaft, and slide the nose back on.

Dan
'91 928GT S/C 475hp/460lb.ft

blown 87

I know some of you guys think I am nuts about Wurth brake clean, but I use it in bulk to flush AC systems with, seems to work far better than any commercial flush kits I have used, and it gets all the oil out.

It is very messy though.

Bill Ball

No problem. That's loads better than a garden hose.