mode actuator replacement

redbandit98

Original poster
Member
Aug 8, 2012
28
Ok.. first off I know its been discussed before as I have read through a few threads. That being said I now have more questions. lol I have an 02 Envoy with the tick tick tick of the actuator every time I start the truck and every time I switch from defrost to dash vents. It has done this since Ive owned it, but its gotten to the point of now when its on the dash vents, half my air is going out the defrost. I know the actuator is out of position due to binding up or whatever. My questions are...I have read threads and got a part number but I'm not sure if its the correct one? I was set to order one online and at the last minute read something about the 02s having a different actuator than the rest of the trucks? I also read about the TSB in regards to the dealers having the tool to pull the actuator without pulling the dash. Going by what Ive read, its seems it can be done without pulling the dash, fairly simply. Do I need this puller to do the job? If so I can make one, I have the resources at work to make pretty much whatever I want. I'm hoping I wont need it, but thought I would ask. Also, when reinstalling the actuator, what position does the damper need to be in? I also read put the "mode" in bi-level before removing the actuator. That would be fine but I know mine is out of position so its not going to be correct..Can I just split the difference, or is there a procedure that can be done that will learn the position? Im sure the actuator has an encoder or pot.. possibly internal limits and can swing both directions and give a feedback for a "home postion".
thanks
Matt
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
I think the 02 has some different part numbers, but I'm afraid I've forgotten when the right ones were posted. Certainly back on trailvoy. Pictures of homemade tools were also posted back over there.

20 seconds with a Google image search got me this link: Homemade HVAC mode door tool - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

The shaft can only go into the actuator one way. And the actuator does indeed have a pot for position feedback, and the essence of the power-on recalibration is so the control module can run the actuator CW and CCW to discover where the physical end stops of the door rotation are. It pushes the actuator until it quits responding with movement, and this stress is what kills weak actuator gears.

Have you read my explanation here: No floor vents - replaced mode actuator - rebuilt defrost actuator still nothing - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum
 

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