2003 Chevrolet TrailBlazer EXT knocking sound

chevrolet
trailblazerext
#1

There is a knocking in the very back of my Trailblazer. It only happens when I first start the car. Goes away within a few sec/min. What is it and how do I fix it

#2

Most likely a rear a/c mode or blend door actuator. Sometimes on this generation of GM trucks disconnecting the battery for a period of time will fix the problem, as the computer will recalibrate the doors operation.

#3

Hello there,
I’ve Trailbalzer 2007, I’ve the same problem above, tried to follow the reset prociedure but it didn’t work, now I need to replace the actuator, it’s the one of the middle of the three on the driver’s side, the problem is I couldn’t reach it from below the steering wheel, do you have a video showing how to reach it?

#4

Look on YouTube