This 2002 Chevrolet Trailblazer came in with a clicking sound under the driver’s side of the dash and erratic control of heat and a/c, hot and cold, air from the driver’s side of the dash. To find the actual site of the clicking noise, I had to remove some of the underside of the dash. Two screws up top.
Two screws under the bottom for the black hush panel.
Drop the hush panel down and unclip/ unbolt all of the stuff attached to it.
Remove the two screws at the lower edge of the knee panel. Lower and remove the knee panel.
Remove the four 10 mm nuts that hold the inner aluminum panel.
Remove the aluminum panel.
The driver floor vent duct needs to be removed. The left end of the duct has a retaining clip in it, that holds the duct in place. You have to either remove the clip or firmly pull down on the left side of the duct and wiggle it until it comes loose.
Remove the hold down screws for the actuator through the openings in and around the bracket, 5.5 mm.
Remove the two 10 mm nuts and the wiring harness clamp from the studs as shown below.
Remove the 10 mm bolt from the leading edge of the bracket.
Now go back and loosen the studs as shown. You will need a torx socket for this operation.
With the two studs loosened from the inner aluminum bracket, grab the sheet metal bracket and pull it towards the steering column. This will allow enough room for the actuator to come out.
The new actuator did not come in the same position as the old when it was removed. You can purchase a new actuator by clicking here.
The old actuator had a part number 16164972 and the new actuator has a label with part number 52402599.
I connected it to the wiring and turned the key on until it matched. I turned the key off as soon as it was in the correct position so that the actuator would not over travel and possibly get stuck.
I do not remember at this time if I left the wiring attached or disconnected it before reinstalling it in the dash. The sheet metal bracket has to be pulled again to get the actuator back into position. Then take your time and push the bracket back into place and align the two studs into the aluminum bracket, so that they will not cross thread.
I hope those speeds are KPH and not MPH. Where does the noise seem to be coming from, front or back of the vehicle? Interior or exterior? The problem with trying to diagnose/locate a noise under those conditions is that you will need someone to ride with you, so that they can assist with locating the sound. If the noise seems to be coming from the dash area, you may want to remove the under dash panel on the driver’s side and the glove box on the passenger side. That it make it easier to feel for the sound.
i have 2002 TB and the clicking sound appears when i’m driving off road or when the car shakes more and sometimes appears when the speed is between 80 to 100 and the clicking goes with i speed more than 100!!
i hope if you can guide me.
By design there will be less air flow from the dash vents when adjusted to full warm. The difference will not be large though. I would suggest visually checking the range of motion of the actuators to see if anything is evident. If everything is moving fine and it is a large difference in air flow, then I would suspect something physically blocking the flow of air through the heater core.
I have an ’03 Trailblazer with manual HVAC. I have low airflow coming out of the dash vents on warm setting but good airflow on cool setting. Is this an actuator problem?
It was indeed one of the actuators. Thanks for giving me your opinion.