Blower Resistor for Chevy Vehicles

Good Answer: from that thread:-

Complete GM Truck Resistor Repair Kit - Only $71.95 -

Just about all makes have this problem. It stems from cheap fan motor construction. The oilite bearings on the fan shaft dry out and increase the load on the motor. As crud builds up on the squirrel cage, load increase on the motor. Condensation in the heater box corrodes connections in the cheesy crimp connections on the resistor block and blower pigtail.

If you can reach the squirrel cage through the resistor hole and turn it with you finger or a screw driver then you can judge just how stiff the bearing(s) are and decide whether a new resistor will be the fix or a new motor needs to be included in the repair.

Bob

I don't have this problem with my FORD truck. Sounds like a good item for recall and class action, obviously shoddy engineering. I was truly impressed with the quality of wiring and o-ring sockets in my 20 year old FORD truck.

I think there are some unclear items ,

First; The blower motor resistor circuitry involves all speeds except high.

Because of the high current requirement of the normal blower motor the switch when placed in the high speed position uses a relay to supply current directly to the motor and does not go through the resistor body.

A blower motor that is burning up resistors should be checked for current draw and I suppose it is possible the manufacturer of the vehicle did not allow enough of a safety factor when specing the power rating of the resistors. Also if there is poor lubrication for the motor armature bearings the draw will be higher than normal and probably cause the motor and wiring to overheat.

What do our Electrical Engineers have to say about this?

h

I'm surprized you have a resistor in the blower circuit. My 92 Buick Roadpig has a transistor driver for the blower. Many older GM vehicles with a resistor in the circuit placed the resistor in the blower vent directly in the air flow. This air flow cooled the resistor to a state it would last. Cooling air flow may be a problem?, but a larger capacity resistor would probably work easier.

Had a Caddy with the same issue....

I soldered in a piece of small gauge solder as a bridge/fusable link and never had another problem.

I had a similiar problem. The resistors were all right but the thermal fuses between the resistors were blown. I needed the high speed that day so I just bridged the thermal fuses out with a piece of wire and crimp connectors and everything worked. I figured the resistors were in the air stream from the fan anyway and would get some cooling. That was 2 years ago and haven't had a problem with it.

Excess motor current isn't the only reason these things fail.These resistors use the flow of air to cool. If the airflow is impeded for any reason ( plugged filter,etc ) they will continue to blow.

Thinking back now, I think there was a lot of snow that day and the air intake probably was blocked. That would explaine the thermals blowing.

Yeah, my '02 Suburban only works on fan speeds 3,4, & 5.

I haven't been annoyed enough yet to fix it. Transistors running in linear mode or PWM sound attractive, but . . .

that violates the KISS principle.

That being said, there sure could have been some characterization of the system over its expected lifetime and provide for some robustness while maintaining system safety. No heat or A/C is more preferable than a fire. We all know the lawyers make the final design decisions so I'm not surprised that the thermal fuses go "so early".

Check for leaves, dried grass, etc. which might impede the airflow.