My heater control fritzed out; smelled like burning wire under dash, then
the controller blanked out.
Dealer thinks its either the heater controller, or the heater resistor
The controller is easy to replace but expensive; the resistor block is
cheap, but is very hard to get to (under dash behind blower motor). Does
anyone have any suggestions on replacing the resistor block?
Answered own question. Trick was to see the schematic from the dealer,
rather than Haynes or Chilton. The dealer's schematic showed the resistor
block sitting on top of the heater assembly near and not immediately behind
the blower motor.
Resistor was discolored but not broken. Will swap test controller to see if
its OK. If it is OK, any ideas on what else could be wrong? I put power to
the fan and the motor is OK, so the problem is between there and the
Look for a 6 pin connector behind the controller and pull it apart. Most
likely its fried. Common on these gmc's.
My connector was directly behind the controller and easy access, I have
heard others say to access it remove the glovebox and it is there.
Good Luck and plz post your findings
Problem had multiple causes.
There was a resistor in the controller module that was blown. My nephew (an
electrician) found and replaced it; saved replacing the entire contoller
The resistor block which looked OK didn't test OK. I replaced it. May have
been the source of the problem with the blown resistor in the controller
The relay (6 pin connector) in a bank of three similar devices in front of
the resistor block behind the glove box (not behind the blower fan as my
book showed) is OK.
There was still no power to the controller module because of a poor ground.
Everything worked except for the fan. Instead of trying to find this, I ran
a new ground the blower motor directly to the frame. Everything now works
but the blower motor is noisy and a little stiff. Probably needs lubrication
or a bearing; will take this apart and repair tomorrow. This may have
contributed to overloading of the resistor in the first place.
I would like to check the filter (if there is one) next to make sure it
isn't clogged with dust. Do you know if there is one and where it is?
Thanks for all the info.
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