Factory AC suddenly stopped working

[mikemileski]

I have a '72 GMC 4x4 with factory air. Occasionally, when I would have the levers in the cold and air conditioning position, I would turn on the fan switch and the compressor wouldn't engage. I would flip the switch to off and then back on and the system would start working. Today after work, the compressor wouldn't engage no matter what I did. When I got home, I jumper wired the compressor and it turned on just fine and blew cold air. Is the culprit my switch? I'm assuming it is but wanted some input here before I go and change it. Thanks.

Mike Mileski
Tucson, AZ