2003 Chevrolet Trailblazer, Clicking Sound From Rear HVAC Unit

This 2003 Chevrolet Trailblazer came in with the complaint that there was a loud ticking sound coming from the rear of the vehicle. From experience I knew that one of the rear actuators was making the clicking or ticking sound. I checked the rear controls and found that adjusting the mode position would make the sound go away but the mode position would not change. I found out that the blend or temperature door was also unresponsive. The bulk of the rear HVAC system is located behind the passenger rear trim panel. This is a fairly long post so I will be breaking it up into several shorter posts.

There are multiple panels that have to come off first before the main cover can be removed. I started by lifting the rear floor trim strip that finishes the edge of the carpet. There sure is a lot of dust in there.

I then turn my attention to the right rear upper pillar seat belt mounting bolt. The cover first has to be lifted by lifting each corner one at a time so that the clips will release.

Once both lower corners are unclipped the cover will flip straight up.

Now the mounting bolt can be removed. A Torx T47 bit is needed.

Next lift the rear rubber seal from the body edge.

I generally grab the upper edge of the panel and pull the panel from the body. Having the rubber seal loose and out of the way allows me to be able to see what is going on behind the panel and gives me access to the plastic edge for better pulling.

Now the right rear door sill panel needs to be removed. You just have to reach under one of the edges and start lifting up. Although the picture gives the impression that I started pulling up from the outer edge, the truth is that I normally start at the inner edge or one end. The angle that the picture was taken at was to show the way that the clips fasten in.

The second row seat belt bolt has to be removed in the same manner as the third row was. This is an EXT style vehicle. Once the seat belt bolt is removed the trim panel can be pulled loose from the vehicle.

There are five phillips headed screws that have to be removed from the rear area of the passenger side panel. Two about half way up the panel and three along the lower edge.

Now the side panel can finally be unsnapped from the body. There are clips along the rear edge, the front edge and the edge just below the side glass.

The panel will slide out either the right rear door opening or you could pull it out of the back.

With the ignition on the clicking noise started and it was easy enough to just place my hand on the actuator to feel the malfunction. The actuator shown below is the auxiliary mode actuator. If you want to purchase the most up to date replacement actuators please click here.

Now that the panels have been removed and the clicking sound identified the next post will deal with changing and calibrating the faulty actuator.