If you own an 86LS gas unit I traced the wiring diagram and found the following: From the AC thermostat power goes to(34) high pressure cut out sw then to (35)hi engine temp cut out sw (upper rad tank) then to(33)low pressure cut out sw,then finally to the AC clutch. This is a series circuit, any poor connention at the switches or plug connectors in this circuit will prevent the clutch geting voltage. At this point there is also a branch wire that feeds the relays for rad cooling fans via (sw 29) and (32). _____________________________________________________________________ 1 Temp sensor in the bottom of the rad..turns the fans on when the coolent gets too hot 2 Temp sensor in the top radiator hose.. turns the air con clutch off if the coolant temp gets too high. plus there are three other sensors: these installed in the funny little manifold coming from the bottom of the condenser. they are: 1 High pressure switch...opens whenever the refrigerant exceeds its pressre setting. 2. Low pressure switch (fan) turns on the fans automatically as soon as it senses pressure when the A C syatem is turmed on. 3 Low pressure cutout Turns off power to the AC clutch if the system looses looses pressure. How it works: When the A C fan switch is turned on, it arms the Rheostat. The rheostat, sends power thru the light blue wire from the overhead-to three switches,(according to its setting) They are arranged in a series circuit which means all must be closed to turn on power to the A C Clutch. So-the power from the blue wire passes thru the closed contacts of the Low Pressure Cutout Switch, closed contacts of the High Engine Heat Clutch Cutout Switch and the closed contacts of the High Pressure Cutout Switch. If all are closed, power is supplied to the clutch allowing the compressor to function. As soon as the Low Pressure Fan Cut In switch scenses pressure it will turn on the fans. Should the engine temperature get exessively hot, it is sensed by the top of radiator High Engine Heat Clutch Shut Off Switch and open the circuit to the clutch turning off the system, same with the High Pressire Cut Out Switch. Hope this helps explain the sysem and its operation. Larry S.