Chevrolet Repair: Air conditioning, ground wires, fan works

Question
My A/C compressor does not work. the fan works but the compressor will not work. The fuses are good. I am not sure if it s the switch itself or a relay.  I have a 1991 S-10 Blazer 4.3L.  There seems to be a switch connected to the condenser tank and I was wondering if that was the relay. I do not want to replace the compressor as I have r-12 and do not want ot convert.  Do you have any idea what could be wrong.  There are two wires that go directly to the top of the compressor.  Both of them seem to be ground wires when I test them. They are green and black.  Is one of them suppose to be a power wire.   Any help you could give would be most appreciated.  I have never had any problem with my A/C except for the occasional recharge
thanks

Answer
Hi Mario, If the A/C system gets low the compressor will not come on. To test this, remove the connector from the accumulator tank and jump the 2 terminals with a piece of wire or paper clip. DON'T push into the terminals just touch them. Do this with the engine running and A/C on, the compressor should kick on when you jump it. If it does you need a recharge or have a leak in the system.

        Let me know how you make out         Mark