Help!!! Blower control module/ resistor problem

Rorybsst · August 29, 2015

I have a 2004 GMC Sierra 2500hd SLT w/ auto climate control. I pulled what was suppose to be the 3 pin control module but there is a 7 pin blower control resistor under the glove box. Has anyone heard of this before?? Pls help I've been beating my head against a wall trying to figure this out or why it's like this. I bought both a resistor and a control module and neither will work

Doug_Scott · August 29, 2015

You do not say what you are actually trying to fix. The module in the heater box contains resistors that give you the different fan speeds. It is very common for them to fail. Usually when they fail they also melt the connector. I do not know 3 pin module you are referring to. Are you trying to fix something by throwing parts at it, and stop throwing once the issue is repaired?

tbarn · September 3, 2015

cj3 = manual blower control

cj2 = automatic temp/blower control

Doug_Scott · August 30, 2015

I would take the part into the dealer parts counter and have them see what it actually is for. There is likely some markings or a part number on it they can use to tell what it is supposed to be.

Rorybsst · August 30, 2015

ok my truck has auto hvac, (cj3)the auto hvac system does not come with the 7pin blower resistor,( resistors are used on manual hvac) mine suppose to come with a 3 pin blower control module, my ac has been out for a while, I pulled it and it has a 7 pin resistor in it. I went to the dealer and they used my vin and got me the new 5 pin module that gm made to replace the original 3 pin module. Ur suppose to cut the 3 wires and splice them with the new module harness plug they give u with the new 5 pin plug. My problem is I have a 7 pin currently

Installed in my truck. With a 7 pin plug.

Rorybsst · August 30, 2015

My module failed on my truck, I'm trying to change it. I'm trying to see what I need to do now. The dealer said they have no idea why my truck has a 7 pin resistor when it should have the 3 pin module.

Doug_Scott · September 3, 2015

ok my truck has auto hvac, (cj3)the auto hvac system does not come with the 7pin blower resistor,( resistors are used on manual hvac) mine suppose to come with a 3 pin blower control module, my ac has been out for a while, I pulled it and it has a 7 pin resistor in it. I went to the dealer and they used my vin and got me the new 5 pin module that gm made to replace the original 3 pin module. Ur suppose to cut the 3 wires and splice them with the new module harness plug they give u with the new 5 pin plug. My problem is I have a 7 pin currently

Installed in my truck. With a 7 pin plug.

cj3 = manual blower control

cj2 = automatic temp/blower control

Is your truck equipped with CJ2 or CJ3? You originally said "my truck has auto hvac, (cj3)". The manual fan control module for the CJ3 option has 7 pins. Check this video from youtube about how to change the module/resistor part.