Hi All,

Posting on behalf of my FIL how is having some issues with his Blazer. Fuse that regulates heater fan keeps blowing on him. He replaced the blower motor so he is confident that is not the culprit. However, heater fan works for a period, but if Fan is turned OFF, then there is no fan at all when turned back on (blown fuse). No other electrical problems present.

Any and all suggestion appreciated.

Best,
Ken

 

Sounds like you may have a short in the fan switch or the wiring to the switch. Ifmoving the switch causes the fuse to blow, then the short is in the speed control circuit somewhere. There is a Resistor Bank in the heating duct under the dash that controls the low and medium speeds of the fan. High speed bypasses the resistor bank and puts 12v. directly to the fan motor. The speed wires go from the switch to this resistor bank and on to the motor.