I evacuated and recharged my ac on my 1990 740. It worked well, but receiver/drier would still begin to freeze after 20 mins of driving. I suspected the lo prssr switch. I removed it and noticed that it had an adjustment screw. I saw that ari posted on another board that he has used this screw. I think that I need my compressor to cycle at a higher low pressure, so I turned the screw clockwise a half of turn. Now I'll have to take it out for a drive and test it. Any thoughts?

You were right, Ray, clockwise makes the circuit break at higher pressure. For a change of 7 psi (lower), I rotated it one or one-and-a-half turns CCW... you may need to adjust it on-the-fly as you drive, in order to get it to work properly. You don't need to remove the switch if you reach from the driver's side of the engine bay with a long screwdriver and cock your head funny.

Let me know how it turns out. If you do need a new switch, they are like $12 at Autozone. It's a generic GM switch.

Ari

Thanks Ari, I'm taking a long trip over the next two days. I'll let you know how it turns out.