Late W126 Climate Control advice?

[krwsenior]

I've been working on my 91 350SDL for about 6 months now to bring it up to a more dependable level. I've made much progress, so now I'm about to tackle the climate control. I've been reading much on the topic. Most post have to do with 123 or early 126 models. I'm not sure how different mine will be.

The A/C works, but does not cool as well as it should. It is charged with Duracool. The high side pressure is lower than usual, the low side is good at higher RPM's but rises to 48-50 psi when idling. Both electric fans are running continuous (wired direct). Vent temps are around 65 degrees idling and will drop to 55 degrees on the highway (90 degree ambient and very humid - Louisiana weather). I'm not sure what has been done to the system in the past other than it was originally converted to R134A, then charged with Duracool.

On the inside, then air blows to the defroster. I blocked them both with new fuel hose cut to length, which diverts the air to the center vents. I dread pulling the dash, but I'm sure I will have to. It has air bags for driver and passenger so this may make it a little more difficult. Occasionally, the compressor will delay turning on when starting up the car. I have removed and put dielectric grease on the pins of the KLIMA module and this seemed to reduce the frequency of this occurring, but it still does it sometimes.

I am going to buy a mitivac so I can test the pods. Any suggestions on where to start on this project? Thanks in advance.