Today I had a chance to open up motor for the fresh air diverter valve.
This is the part that makes the clicking noise when you first turn your key on. The clicking would last for 5-15 sec.
From the image we see the larger white gear. This is what couples to the fresh air blend door / diverter valve. It is geared down by the blue gear, red gear, yellow gear, and driven by the red worm gear on motor.
I am willing to bet that when the door closes, power is still applied to the motor until the white gear jumps a tooth or two and makes the click.
Notice the small diameter of the blue gear engages the large diameter white gear.
This is a rather large gear ratio and over time, wear on the plastic bearings (bosses) and the stress between the blue gean & white gear, the teeth just give out.
Now this motor was held on by only one plastic retaing clip and the 2 lead electrical connector.
It was quite easy to remove..........
The entire dish pad, passenger side air bag, radio bezel, glove box, insterment cluster bezel are removed.
And if fortunate, none of the trim pieces crack or breake as they ar removed.