To recap: Condenser coil on my '00 300m was punctured back in early February. Ok - didn't needed it for the next few months. About a month ago I replaced it (Rock Auto). Replacement fit nice, came with seals blocking the 2 ports. Removed the seals and heard hiss of air - either it was pressurized or vacuum-ized at the factory. Either way, I guess that means it has no leaks. Original line fittings were clean and the seals looked good. Today I'm messing around with "Red Tek" r12a recharge kit. The high and low ports on this car seem to be mounted directly to the compressor - not in-line on the hoses that a lot of youtube video's show. If there's only supposed to be one port with a plastic "H" screw-cap, and one port with a plastic "L" screw cap on this car, then they're mounted directly on the AC compressor. And you have to take the oil dipstick out because the handle is in the way of the Low port. So I follow the directions and screw a bottle of r12A to one end of the line that comes with the kit. There is a pressure guage on the line, and a slip-ring fitting on the other end that connects to the Low port. Connect the line to the Low port - it reads zero. The High port has a slightly different fitting - so I can't measure it using this guage. I turn the can upside down, screw in the point that pierces the foil seal, and I hear something flowing. I have to be careful that the slip-ring fitting stays plumb on the Low port because and rocking or angling of the fitting breaks the seal and I hear a leak at the port. Why can't they design these better? The pressure quickly climbs to 80 (PSI I guess - according to the printing on the guage). Here's a closeup pic of the guage: http://www.gmforum.com/attachments/...dtek-ac-equivelent-2lbs-r134-qty-img_3670.jpg It didn't feel like the can was empty, but no more of it was flowing into the compressor. BTW, the engine wasn't running while I was doing this. I screwed the needle valve on the can closed and removed the line from the Low port. Then started the engine, then turned on the AC. Got nothing but warm air. The AC was on - was making a bit of noise. Ran for about 30 seconds and turned off engine. Reconnected the line to the Low port - pressure was maybe 70, opened needle valve to let more in, pressure went up to 90 quickly. Started car again, still no cold air. At this point I'm thinking maybe this pressure is too high. I stick a pointy tool into the high-side valve and yes - lots of pressure there. I mess around letting some gas out of both low and high ports and get to a point where I let out all pressure from High side and bring the low side to about 30 (psi?). Start the car, get maybe some cooler air, but not worthy of a working A/C system. I notice (with the engine not running) that letting gas out of the high side does reduce the pressure on the low side - don't know if there's supposed to be an air-tight seal inside the compressor between the high and low side or not. I don't get why, with a system that clearly was equalized to ambient pressure before it was sealed by installing the new condenser, why it would take less than half a can of this stuff to bring the low side to a pressure like 80 (with the engine not running), and why (after starting) the pressure didn't immediately fall to allow more of this r12A to be injected. I should have needed 2 of these cans to bring me to the equivalent of what I had with 134a.