1972 Cutlass Supreme U code 455 with factory A6 compressor, system was converted to R134. Started the car last week, took it out for a spin and noticed A/C was not working. Checked under the hood, and when I turned the A/C on the compressor would turn on but it would not cool. I suspected that I had a leak. Last time it was refilled we added Dye, so I took out the UV light and found out that the 2 seals in the back of the compressor were leaking, everything was green there. I ordered new seals and I am waiting for them. I obviously need to open the system to change the seals and I will need to vacuum the system to be able to refill it. The question now is what about the compressor oil? Will I need to add oil when I refill it? If I do how much? I am new to A/C, when I was young we took the A/C stuff of cars to go faster, never really learned to work on them, but I am going to learn now...

 

When you open the system, try to catch any oil that may drain out of the compressor, then add that much back into the system.

 

That sounds very reasonable. I guess I will try and figure out how much is lost and then refill. Wouldn't some oil have been lost through the refrigerant leak? Or would that just be a negligible amount?

 

How much oil residue is around the leak area? Keep in mind that one drop of oil can spread quite a bit.

 

I need to check again, but it does not seem to be a lot.

 

If I were you I'd tear down your compressor & reseal the whole thing, just to be on the safe side!. I had the same problem on my '68 442. It was already "converted to R134a" before I bought it. It had a fairly recent parts store rebuilt compressor on it & the a/c worked ok, It got cool but nothing to write home about. It developed a leak at the rear of the compressor, I thought it was from the 2 hose o-rings but it ended up being the large internal case o-ring at the rear. When I took the compressor apart it still had the black neoprene o-rings inside. These are NOT compatible with R134a. You need the silicone o-rings (green colored)for R134a. The green ones work with any type of refrigerant. The R134a/oil combo also attacks paint, I had to pull my restored right side suspension back apart & refinish everything!! Not a happy camper!! I was able to get a hold of some R12 so I flushed everything out, added the the correct mineral oil from Napa Plus a new receiver/drier.(The POA valve was still set for R12). It A/C will freeze you out of the car now!, plus if it does ever leak the R12 oil won't hurt any painted surfaces.

 

I have been thinking about doing this as I know that all the seals inside the compressor are not correct. I did order all the correct seals for the compressor, so I may just end up opening it up and changing all of them. Hopefully this is not too difficult as I have never done it. I did see that there is a video on YouTube on how to do it. So I guess to YouTube school I go again :-)

 

The utube video I saw was excellent! It's been years since I had a compressor apart. I bought a kit off of ebay & it also came with an updated 1 piece seal & a sleeve tool to install it. The guys video I saw even covered installing the new style seal! How did we make it before utube???🤣🤣🤣

 

I know I used to buy the Chilton book for the car. As a kid I would go to repair shops and work for free to learn :-) I learned how to rebuild Holley carburetors, and a lot of other stuff, from a guy that had a shop called Marrero Racing. Learned to pull engines and rebuild them from a guy named Luis, who was a former mechanic, but had gotten a job in the local airport that paid very well, he helped me pull the engine from my 72 Rallye Charger factory 440 magnum car and rebuild it. That guy died young, not long after doing the engine in my Charger, from colon cancer. He had a 1969 Roadrunner 440 six pack, 4 speed, dana car in front of his house that looked like it had been sitting in front of the beach for years, car was all there but had a TON of rust. Worked a month for free in a body shop to have them teach me how to fix my uncles car that I crashed while doing a little impromptu street racing. Had a neighbor that was a VW enthusiast and he was always building a VW, I would help him. That is how it used to be.
Now we have great people in these forums that are willing to share their knowledge to help others. It's kind of the same but different, we used to have hands on help from neighbors, friends, and just great random people that we would meet on the street, and now we get the same help from our virtual neighbors, friends, and random people in these forums and on YouTube. There is a special feeling of accomplishment that comes from helping others, and that is spirit of helping others is especially present in the automotive community.