Fan relay

96 gmc jimmy. I keep blowing my high speed a/c fan relay. Any help on what will cause the relay to blow will be great. on the relay the wires going to it and the relay it self have a melted spot. the fan on the a/c works but will not go to high

What color wire is burning on the relay? Burnt wires is a sign of high resistance, could possibly be the blower motor going bad, or a bad ground for the motor. For not working on high speed, have you checked all fuses, both sides, with a test light or voltmeter? Possibly the heater blower resistor is faulty, or open circuit somewhere.

i checked today and its the red wire. the only one that is a heaver guage wire than the rest and plugs into number 87 on the relay it self. someting eles i just learned is that the switch on the dash will sometimes go past the highest setting could that be my problem? dw just told me about that!!!

It's possible that the switch could cause high resistance, but it's not likely with the relay terminal burning. The two most common things for high resistance in the blower circuit are the blower motor itself, and the blower resistor. The fact that the blower motor feed wire on the relay burnt, would indicate that the most likely cause is high resistance in the blower motor itself. Best to check amperage draw of the motor before replacing it. Seems to me that maximum amperage draw for the motor is around 20 amps.