Well, here goes. My mechanic says with barely looking at anything that it is the evaporator that is leaking. Something leaks because the charge doesn't last more than a month or two. I guess he is so used to the evaporator problem he can spot it 'just like that'. I was reading online at "keep-it-kool.com" that they sell an a/c leak repair that you add to the system. Another mechanic told me that he won't use it, not because it won't work but because it could clog up a recycling system should the system ever be evacuated by another shop. I am going to buy the guages, a vacuum, a dryer, and the sealer and do it myself. I don't have too much to lose, a $150 compared to $1200. More than just not having $1200 to spare i can't see spending almost a third of the cars' worth to fix a evaporator leak. Anybody have anything comments or heard about the sealer?

Use a valve tool to tighten the schrader valve, if it might be loose. Most cans of r134a contain dyes (yellow) which can be seen with UV light.
NAPA sells a 3oz can of leak stopper which must be chased by a can of r134a. It will stop most leaks. Just remember, AC shops refuse to evacuate any system with leak stopper in it, because it destroys their equipment. AND, if the leak persists you will not only need a new evaporator, but a new drier, hoses, condenser, etc. So says my local AC shop.
I just keep adding r134a at $11/can.

Klaus
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1975 164 w/173,500mi 1995 850T w/91,000mi, 1998 V70R w/128,000mi

thanks klausc. could you tell me where the schrader valve is and also why would i need to change out everything if only the evaporator leaks?

thanks again.

The schrader valve is where you add r134a to the system, directly behind the right headlight.
IF you use a 3oz can of leak stopper, it will gell when it gets in contact with air. So... if you then decide to evacuate the system, the leak stopper will gel where ever it gets exposed, which is everywhere. Most AC shops refuse to work on a system with leak stopper in it.
If you buy a can of r134a which includes a "leak sealer", that is OK because it is such a small amount and will not have a negative effect on AC equipment. It normally does not stop evaporator leaks.

Klaus
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1975 164 w/173,500mi 1995 850T w/91,000mi, 1998 V70R w/128,000mi

The evaporator is most likely the culprit, BUT is not 100% of the time.

The schraeder valve at the charging port can leak and easy to detect if you have dye in the system.

If the charge holds for a couple of months, then the leak is small. Before you take the dash apart, recharge the system with refrigerant can that has dye and stop leak. The stop leak approach is a one time deal. It will work if the leak is pinhole size. If it discharges in a couple of months, you know the leak is big enough and you can trace the leak now with the fluorescent glasses.
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'88 240, '92 745, '98 v70 -John, Tampa Bay