Review on Dorman 604-112 Blend Door Actuator: High-performance HVAC Control for Select Models by Victor Ewing

My 2008 GMC Sierra with Dual Climate Control started blowing random hot air out of the driver side vents. You can turn off the ignition, then it will go back to normal or almost normal. I finally got fed up and looked for a solution which was the mixed door motor. I have used Dorman parts in the past and had good results. There are 4 screws to remove the under dash cover on the passenger side. Then 2 screws on the part itself. To remove the connector you need to press the latch and at the same time pull out the connector. I removed the old motor, then put in the new one and connected the connector. It worked as advertised and now my truck is blowing very cold air out of all 4 vents. 2 important things. 1) Don't move the white drive on the part you may damage. A warning is printed on a piece of paper on the box. 2) You may need to reinstall the air system in your car before it will work properly. The easiest way to do this is to disconnect the neutral cable from the battery and leave it for a few minutes. Then plug it back in and get in your car. Insert the key in the ignition switch and turn it on (DO NOT START THE VEHICLE). Let it sit for a few minutes. It will cycle through and reset everything including indexing the faucet door motor.