a/c -heater fan speed

[nc87k5]

My blower motor will only blow one speed, on low. The motor is working because I can hear it running when the truck motor is not running. How do I determine if it is the switch on the fan control or the resistor in the housing under the hood?

 

[dyeager535]

Check voltage on the plug to the resistor pack when you put the switch in the various positions. Will be 12V on each respective speeds wire as you move the switch.

 

[75K5]

mine did this, I had a broken wire from the heater controls to the relay.

 

[dyeager535]

How is the relay setup? Isn't that only the "high" (straight 12V to motor) position? All other positions are 12V run to the resistor pack, then motor, no relay, right?

 

[75K5]

I'd have to check the diagram, but I think the high speed is a direct wire that doesn't go to the resistor pack.

I think your instructions are probably the best first step.