Automotive Air Conditioning Information Forum (Archives)

wptski on Fri July 19, 2013 7:35 PM

Year: 1990
Make: Buick
Model: Century
Engine Size: 3.3L
Refrigerant Type: R12/R134A

Got my compressor rebuilt after finding a leak at the shaft and rear manifold, no Black Death.

I'm thinking about trying R134A before going back to R12, not sure yet. I've never read that one must remove the orifice tube just to replace the "O" ring but since it probably isn't R134A compatible, shouldn't it be changed?

It's not easy to get to on this vehicle and I've read an old post, I think in this forum that one must remove part(s) of the front end to get to it. I can get two wrenches in there but as long as some animal didn't over tighten it, I could remove it.

webbch on Fri July 19, 2013 10:45 PM

If the system currently has mineral oil in it, you need to flush all the components and lines to get it out, then add back an oil compatible with 134a. That typically means disconnecting all the lines, at which point you'll be replacing all the o-rings in the process (they're cheap anyway, just plan to get them). If you want to keep your options open for the future to convert between 134a and 12, use ester oil instead of mineral oil.

When you're flushing the lines, you probably need to remove the orifice tube anyway. If you just stay with R-12 (getting harder to find, but still a viable option), none of the above may be necessary since you didn't have a case of black death. However, with R-12, you want to make darn sure you don't have any leaks, as replacing the refrigerant if it leaks out is a lot more $$. When I do it, both a vaccum AND pressure test is in order before charging with the "precious" R-12 :-)

wptski on Sat July 20, 2013 9:30 AM

This is the second of two vehicles on R12 unlike the first which I had five 12oz cans. Put in one can which held for days but this one didn't and I paid $25/each for four cans! I then find out that one should use R134A as a static charge for leak testing which is the plan at least to start.

I got an "O" ring kit, POE oil, tools and accumulator from AMA. I got the POE because it can be used with both R134A and R12. I've read(how true?) that residue and even small amounts of mineral oil will be tolerated if POE is used.

Although the compressor had an oil film that was it and nothing in the accumulator either! Unless it lost the Freon fast, not sure where it went. There is a splatter track on the radiator and the compressor was covered with a sticky goo. I think it was "Iceman" that mentioned in another post that if a system is under charged, oil pools in the evaporator. That's 8oz of oil that went somewhere. If it's in the evaporator, it seems that any sort of pressure at all would force something out which it didn't.

This is a family backup vehicle, only 20K on it, seldom driven and all of a sudden last summer, no A/C but did have about 2psi charge in it. More than likely lost the charge while not in use during colder weather.

The evaporator connections being between the engine and firewall has to be the worst to get to. If one can even get wrenches in there, not sure if they be moved at all