More AC - 90 CQ

[Max Baker]

Hi List,

As long as we're on AC problems here, I've got a 1990 CQ with the AC
Delco-style automatic climate controls.

The problem I'm having is that the AC cycles on and off at about a 45
second period.  I set the controls to auto/LO/fan high and rev'd the
motor.   I can see the clutch on the AC compressor coming on and off at
the 45-second interval.  It's very annoying while driving because the car
lurches a little every time the compressor comes back. 

I'm hoping it's just low on coolant and I can find some R12, but does
anyone have any other ideas?   I still haven't found a Bentley for this
car, so I don't have the factory service checklist for this AC system.

Thanks!
-m