My good friend and pastor has this '94 Toyota 2WD, 5 speed pickup he refuses to let go. Probably because he knows I'll work on it for the cheap. Anyway, the fan speed control switch continues to fail, read melt, due to, I'm guessing, too much resistance in the circuit. When the switch housing melts, it becomes stuck on one speed. I've replaced the wiring harness and the resistor block. The only thing I have not replaced is the fan motor itself, but it seems to run fine. How can I measure current in this circuit? I'm surprised the fuse doesn't blow but it never has. I've tried cheaper speed control switches and more expensive ones. One other question. The truck has an A/C system and it did work a year or so ago. The owner says it is an aftermarket system but it sure looks like a factory system to me. Where is the best place to purchase replacement parts for the A/C? I'm going to see if it will hold a vacuum first. I do know the compressor must be bad as the system will not build any pressure. Thanks for any advice!!

 

Measure current in the circuit???
Put a DC ammeter in series with the hot wire that supplies the switch.
If the fuse never blows, you might safely temporarily remove it and bridge the contacts with the ammeter leads.