Last summer I replaced the compressor, dryer, and expansion valve in my 300TD as well as o-rings at each of those places.

refilled with lubricant and R12 and all was good.

Now the AC is acting weird again. it takes about 10 min for the compressor to engage. If I feel the tube in front of the valve cover, it is uncomfortably hot.

last week I put a can of R12 in and the L.P. side went to 35 and held, but yesterday it was at 20. (That is when the compressor is on)

I see movement in the dryer watch glass.

When I scanned the system with a leak detector, I got nothing under the hood (tested joins at dryer, tubing to compressor, joints at compressor), but I did find a few blips inside the car. Mostly when I held the detector in front of the vents. Not alot though, just an occasional blip. When I removed the kick panel and put the sensor tip near the expansion valve I never really heard any blips.

This is bad isn't it?

__________________

Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT