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History: I have the Automatic Temperature Controls or EATC. My blend door motor was dying when I bought the vehicle. You could hear it making a thump-thump like a gear missing and it wouldn't go into full cold. I ran with the actuator out for a while and just moved the blend door manually with my finger.

Installing the new Blend Door Actuator: I got the Doorman (http://www.amazon.com/dp/B00HRI24CK).

I was told (not sure if this is true now), they are configured for Cold out of the box. I turned on the EATC without the actuator plugged in. Switched my EATC to 60 degrees (100% cold). Turned it off. Plugged in the new Blend Door Actuator. Held it in my hand (did not actually install it in the airbox yet) and could turn it from cold to hot by changing temps and watched the drive shaft go from full clockwise to counter-clockwise and back again. Switched the actuator back to cold (clockwise). Stuck my finger in the airbox hole and turned the blend door to cold (clockwise) so they would match. Installed the actuator in the airbox, switched EATC from cold to hot and watched it turn. Then, tried going back to cold. Nothing. Did a diagnostic test and the EATC showed up with 6622 - blend door failure. Actuator would no longer function in the airbox or out of the airbox. But, if I clear the codes, it then functions again. I tried re-calibrating to start out hot, with no success. I tried starting at 75 degrees because that seems to be what the EATC always resets itself to after a diagnostics code clear operation. No success. I tried a good 10-15 times. Each time, I can get the Actuator to work in my hand. As soon as I attempt in the airbox, it hits an either full hot or cold position and won't do anything after that even after taking it out of the airbox. I have to clear codes to get it working again.

Question: This is obviously not as simple as it seems. What is the actual correct procedure? Does it sound like I have a bad EATC or something else is going wrong here? Maybe I got a bad actuator? Maybe short in the wiring? Feels like I'm just attempting this the wrong way.

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Ok. So, I'm a little embarrassed since this solution was simple. Here's what I figured out:

You'll notice, if you're reading / attempting this, that running a self test of your EATC (by pressing Floor+Off Simultaneously, releasing and then pressing Automatic button within a second or two.) will likely generate a 6622 error code (Blend Door Malfunction.) Which may or may not have led you to replacing the Actuator. You'll also notice, that when running the diagnostic self test, the blend door will do a full range of motion from full cold (clockwise), to full hot (counter-clockwise.) This is the important part, as it would appear the EATC is learning the range of the Blend Door. If you do this with the Actuator NOT inserted into the heater box shaft as I did, it gets a full range of motion which is different than that of the actual door itself. This was my mistake. The diagnostic self test needs to "learn" the range of motion with the part installed. Just install the part (don't over think this like I did) and then run the self diagnostic test right away. Clear the codes if there are any (by pressing Defrost once the test completes and is flashing the codes.) You may have to do this twice, it would appear the EATC has to learn the range of motion with no codes present. So, clear codes, then run again and exit diagnostic mode. You should be good to go after that.

Hope that helps someone!

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