[JonathanS]

What is the proper refrigerant pressure in the A/C system of a 1996 LSi?

I seem to have an A/C leak in my recently purchased SVX When I inspectd it prior to purchase about a month ago, the A/C wasn't working. The seller said that it hadn't been recharged in several years, We agreed that she would have the A/C recharged and inspected to make sure that's all it was. The shop put UV dye in the system and reported that there were no leaks visible. When I closed the deal and picked up the car, the A/C was working fine.

About two weeks later, the A/C stopped working. Since the shop that did the original check is over an hour's drive from my home, taking the car back there would involve taking a day off from work, so I can't realistically take it back there.

Today, about a week later, I purchased a UV lamp but didn't see any signs of a fluorescent dye. I then bought an Interdynamics recharge kit with guage and also some UV dye. I added the UV dye (thinking that perhaps the garage's dye had been worn/washed away) and let the system run for about 10 minutes, per package instructions. Still no leaks visible.

I did check the refrigerant pressure, however, and it was low, at around 18 psi. I recharged it to about 27 psi. I think the 19 oz. refrigerant canister ran out at that point. The Interdynamics packaging said that the "filled" range is from 25-45 psi at 75-85 degrees F. Since it was about 68 degrees when I filled the system, I figured I had added enough.

Did I? I don't have a shop manual, and I couldn't find any A/C specs in the owners manual.

I plan to check for signs of fluorescent dye and keep track of the A/C sytem pressure a couple of times this week. I would appreciate input from fellow owners on the following:

-- What is the proper A/C system pressure?
-- Why am I not finding leaks? (I am guessing that there is an internal leak, say in the compressor or elsewhere, that is collecting the dye internally.)
-- I also picked up some Interdynamics two-part A/C leak stop. Part one is supposed to fix metal-to-metal leaks and part two is supposed to fix rubber leaks. Is there any reason not to just dump it into the system?

Thanks in advance from a novice A/C tech ...