Easiest way to is to pull the AC fuse so that no juice goes to the solenoid. I don't know where it is, though.....
I have the Chilton's manual, very small diagram, very hard to read. I'll see what I can find there.
Do you have the automatic climate control? If so, it may be bad.
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!