The reason I originally suggested that your vent temps and pressures are wacky is because they are, at least to me. With the rear A/C off, you have vent temps of 36-38 degrees, which are pretty cold. With the rear A/C on, the temps range from 47-54 degrees, which are on the warm-ish side. Such a wid...

Your varying pressures and vent temps are certainly wacky. Are you sure that the charge is still correct and that you don't have another leak someplace? I suggest recovering the charge to verify that first.

I'm wondering about a few things. Since you mentioned an aftermarket "side-mounted" condenser, is the entire system aftermarket? If not and the rest is OEM, does it have front-and-rear A/C or front-only? The reason I ask is because there's a substantial difference in the amount of refriger...

DEFINITELY DON'T ADD ANY SEALER TO THE SYSTEM. Doing so will only create more very costly problems. Find the leak, repair it, evacuate and recharge the system, and you'll soon be driving in cool comfort again.

I agree with everything that Tim and Cusser said, especially about the leak. If you live in the Northeast where most towns and cities use tons of salt on the roads to melt snow and ice, you might have a pinhole leak in a hard line due to corrosion, which in turn would cause a slow loss of refrigeran...

It's possible that it might need a little more refrigerant, but with these conversions, it's hard to tell what the exact charge should be. Still, I don't think the refrigerant amount is your problem unless by some fluke the charge you put in it has leaked out. Even if the charge was a little low, yo...

Hello, Wren. Usually, a vacuum reading on the low-pressure side does indeed indicate that the TXV is defective (not opening enough, if at all) or there is some kind of restriction in the high-pressure line feeding refrigerant to the TXV, such as the old receiver/dryer whose desiccant bag has broken ...

To your knowledge, has the A/C system ever been serviced over and above what you guys did to it last year? From what you said, the evaporator case must be in the engine compartment and not under the dash, where it would be more accessible but still not very easy to get to. If sealer was never introd...

Cusser is right, of course. The system has a leak someplace. The hard part is finding it. With a car that old, it could be leaking from literally anyplace. And just because it held a vacuum or negative pressure doesn't mean that the system won't leak when charged under positive pressure. I'd start b...

Scott, A few questions. What make and model of vehicle are you working on, and does it have factory A/C? You said that as you began charging it (through the low side), the low pressure shot up to 115, but the can wasn't emptying. Since you then immediately shut everything down, how do you know the c...