Yet another AC question...

When I bought the car the AC didn't work. A rebuilt master control switch, a new drier unit, rebuilding the monovalve, and recharging the system took care of that, and the AC worked great until last winter when the bracket for the AC pump came loose from the engine block, causing the belt to snap. "Oh well, I will take care of that when the weather warms up" I said to myself. Bad call...

Now with a new belt installed I can only get AC if I manually apply voltage to the pump wires. Otherwise, the pump never engages. I have voltage to the monovalve no matter where the switches on the dash are set to.

Where should I go from here? I really don't want to replace that switch unit...