condenser motor/Fan not kicking in?

The fan is good as I tested it directly. But for some reason it won't kick on while hooked up and with the air running. Is there a sensor that controls it that I could check? Any ideas what the problem could be? If I need to check something if you could tell me where it is that would help as I am sort of a newb when it comes to cars but am a quick learner.

97 Suzuki Sidekick

Check the condenser fan relay. Swap the relays of A/C compressor(if compressor works normally) and the fan. Look for loose wirings on the fan relay.

Mine is a little bit strange the fan intermittently engages while I turn on the ignition and when I switch on the A/C there are times the compressor goes on and off quickly while the condenser fan works normally. I traced the problem to a faulty A/C amplifier. There was a cold solder on the board.