Air Conditioner low-pressure switch connections?
 

I have a 2000 LeSabre with 150,000 miles.
It has the original spark plugs and Battery :)

The AC has been wacky since new.
So has the heater.
I suspected a common sensor.
The dealer suspects I'm wacky.
I would never go back there.

Now the AC has quit.
I got a can of coolant/oil/sealer.
It says the compressor must run to suck the coolant in.
It only runs if I pressurize the switch with air.

I'd like to over-ride the switch electrically.
What do the 3 contacts control?
Which ones must I connect to engage the AC clutch?

Thanksa buncha

Nevin