I'm not sure where the parts live on that car. Usually the blower motor and resistor are in the heater box under the dash, but GM does put them on the firewall sometimes.
Is it the motor or the resistor you're working on? The most common failure is a blower that only works on the highest speed. That is caused by a tight motor that draws excessive current as a result, and that overloads a thermal fuse built into the resistor assembly. With that thermal fuse burned open, all the speeds related to the assembly are dead. The highest speed bypasses that resistor so it still works.
When all the speeds still work, the resistor and its fuse are still okay, but if the motor is drawing high current, or when people use the heater on the higher fan settings a lot, that high current starts to take its toll on the connectors. As they slowly degrade, a little resistance develops, and that results in heat build-up. That heat further weakens the connection, and that causes more resistance. Eventually you reach the point where the terminals get so hot, the plastic connector body melts.
When it hasn't gotten that far yet, that's when it's okay to clean and tighten the mating terminals.
Sunday, April 12th, 2015 AT 2:18 AM