Chevrolet Repair: Heater Blower Inop on 5th speed, chevrolet 2500, deg c

Question
2005 Chevrolet 2500 Diesel, on really cold morning -25 deg. C. Started truck with fan on 5th speed  ran for a bit than quit. 1-4 still work. Changed the blower resistor didn't help.
Fuse is good.

Any suggestions???

Answer
Hey,

 When the selector is on hi speed all of the resistors are bypassed and  the blower motor relay engages and gives full voltage to the motor.  If the wiring and resistor module are ok (the blower relay is part of the resistor module) then it has to be the switch.  On high you will have 12v on the orange wire.  If no volts then it needs a switch.  if has 12v it still needs a resistor.  I have had defective delco ones before that were brand new!


Wayne Howie