Can someone help me locate the resistor pack in the truck? Perhaps a video link of it? The high does not work but the lower three speeds do work. I've changed the one in my wife's Trailblazer, so my assumption is that, that's the issue. Any help is appreciated thanks in advance.

 

resistor for what.....fan speed?

 

Sounds like resistor for the fan speeds.

Front or back?

 

The fan resistor is located in the plenum under the dash next to the fan. You may also want to check the fan speed switch in the dash cluster.

 

If your high doesn't work, and the rest do, then it most likely is just a fuse. Check both fuse locations for a blown fuse. The high speed is run directly off 12v and bypasses the resistor IIRC.

Brew