Best AC O-rings for R-12?

[JHZR2]

I bought my 300cd a decade or so ago, and I knew it had some history of AC leaks. I have all the receipts for the life of the car. But it was still R-12 and it blew cold when I bought it, and any leakage was slow enough that for the three or so years that I used it before kids, I never added any. Then the car sat for ~6 years. And there was no pressure at all in the hoses. I've been slowly getting the car back going again, doing some updates that I had meant to do, and others that have popped up. It was nice and cool until recently - now heat is here. So I wanted to troubleshoot. I don't have bone dry nitrogen or R-22 for troubleshooting, but I could get some ES-12a for off road troubleshooting. I also got dye. So I installed this, and have run it a few hours. That stuff really does work well btw. I wanted to pull my blower to lube the bushings, and to see if there was any sign of leakage via I've or my bc sniffer. I had been unsuccessful seeing any leaks, even at the R-4 compressor clutch and ports. But when I pulled the kick panel, I saw this: And this! After I pulled the blower, I saw this: I'm guessing it's just a bad o-ring, and the leaking refrigerant takes oil with it. Nothing under the kick panel is particularly oily. The noise insulation has some on it, but it isn't sopping wet or something. I guess the time without r-12 and oil on the seal caused it to dry and crack. So what is the best O-ring type and manufacturer for R-12? Ultimately I intend to go back to using that, once any leaks are found and fixed. And it seems best to start with this one...

 

[chemman]

I have read that the HNBR are the best o-rings for HVAC work. If it were me, I would go with 4-Seasons o-rings. Also, I would recommend getting some Nylog Red (RT-200R) o-ring/gasket sealant and using it to lubricate the o-rings prior to installation. That stuff is great!! Here is a link: https://www.amazon.com/Refrigeratio...ords=nylog&qid=1591593302&sr=8-3 Good luck!

 

[demarpaint]

Subscribed. I have an R-12 system O-ring project to tackle later this week, hopefully. Thankfully I have R-12 on hand.

 

[WyrTwister]

Originally Posted by chemman

I have read that the HNBR are the best o-rings for HVAC work. If it were me, I would go with 4-Seasons o-rings. Also, I would recommend getting some Nylog Red (RT-200R) o-ring/gasket sealant and using it to lubricate the o-rings prior to installation. That stuff is great!! Here is a link: https://www.amazon.com/Refrigeratio...ords=nylog&qid=1591593302&sr=8-3 Good luck!

Yes

 

[Lubener]

About 15 years ago my 87 Ford R12 system went empty over the winter. Leaks usually leave an oily residue. I had a few. I bought the tool to disassemble the spring lock couplings, disassembled and replaced ALL o rings at every joint in the system. There were two o rings at every coupling. I went to the dealer for the o rings, they had an assortment pack. I lubed each new o ring with refridgerant oil. I evacuated and recharged the system with R12 and it still works perfectly to this day.

 

[mk378]

That looks like it is running down from above, likely the core is leaking. The most common place for o-ring leaks is the line from the compressor to the condenser, because there the refrigerant gas is hot. The heat hardens the o-rings and then they leak. Always pre-emptively replace those o-rings when you have an old system empty. You don't have to replace every one in the system.

 

[Chris142]

The green ones that are common now work well for R12. One of my customers goes by "rollguy" on the MB forums. He sells a kit to put a Sanden on there as well as condenser upgrades.

 

[Chris142]

Originally Posted by Lubener

About 15 years ago my 87 Ford R12 system went empty over the winter. Leaks usually leave an oily residue. I had a few. I bought the tool to disassemble the spring lock couplings, disassembled and replaced ALL o rings at every joint in the system. There were two o rings at every coupling. I went to the dealer for the o rings, they had an assortment pack. I lubed each new o ring with refridgerant oil. I evacuated and recharged the system with R12 and it still works perfectly to this day.

Your FS6 compressor does not leak? Amazing!

 

[JHZR2]

Originally Posted by Chris142

The green ones that are common now work well for R12. One of my customers goes by "rollguy" on the MB forums. He sells a kit to put a Sanden on there as well as condenser upgrades.

Yes very well acquainted with Rollguy over on peachparts. I may go the sanden route when these R4s quit. For now I just need to figure out what exactly is leaking. Almost looks like its coming out the side. Curious if that is possible... the expansion valve looks like this: Some better pics are here: https://dieselgiant.com/repairyourac.htm Mine: I think perhaps it is the top or bottom right line? Apparently the upper lines are the evaporator in and out lines. The lower right line is the high pressure liquid line going to the expansion valve then to the evaporator. The lower left large line is the vapor or low pressure line going back to the compressor.

 

[Lubener]

Originally Posted by Chris142

Originally Posted by Lubener

About 15 years ago my 87 Ford R12 system went empty over the winter. Leaks usually leave an oily residue. I had a few. I bought the tool to disassemble the spring lock couplings, disassembled and replaced ALL o rings at every joint in the system. There were two o rings at every coupling. I went to the dealer for the o rings, they had an assortment pack. I lubed each new o ring with refridgerant oil. I evacuated and recharged the system with R12 and it still works perfectly to this day.

Your FS6 compressor does not leak? Amazing!

No, it was a HR980 compressor.