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2003 chevy trailblazer_lt
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6 Posts
Discussion Starter #1
I've read all the threads on how to replace this thing, but I can't see what's wrong with the one I've got? I can only get heat in all modes out of the drivers side vents. I pulled the blend door actuator off and did not see any stripped gears whenever I took it apart. I reassembled the cover on the unit and plugged it back in and it actuated fully clockwise and stopped. It would not move when the hot/cold slider was moved. I unplugged the unit and pulled it apart again, moved the gear and reassembled it. Once again, I plugged it back in and it moved completely one way and stopped. Is something broken in the actuator control within the actuator or is the in dash control module broken? Any ideas?

Background: I pulled the battery cable off a few weeks ago and since then it has benn inoperable. I attempted resetting the system by disconnecting the battery again, but it was still inop, I swear I can hear it trying to calibrate, but it doesn't do anything for the temp control. Also, is the blend door shaft supposed to be moveable by hand? I swear I cannot twist it with my fingers.
2003 tb
Lt, dual zone hvac non digital
4.2 2wd

Passenger side works fine.

Thanks!
 

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2009
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1,088 Posts
You didn't read enough. If you are only getting heat out the driver's side then the issue is with the driver's side temp control actuator. It sits below the one you removed. I would have thought that in your searches you would have found that info. The mode door actuator has nothing to do with temp. It just controls where the air comes out whether it is the dash vents or the floor.
 

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2003 chevy trailblazer_lt
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6 Posts
Discussion Starter #3 (Edited)
maybe I didn't express that clearly, but that is the one that I pulled off. It was the lowest one on the drivers side behind the metal brace. I just called it the blend door, meaning heat / cold blend, not mode actuator.
 

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2003 chevy trailblazer_lt
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6 Posts
Discussion Starter #4
Ok new news, re aligned the sensor gear in the actuator and whenever the truck is started it will run lock to lock and return to the full hot position. I assume this means that it is the control panel and not the actuator? Is there a way to check the control panel signal?
 

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Ok new news, re aligned the sensor gear in the actuator and whenever the truck is started it will run lock to lock and return to the full hot position. I assume this means that it is the control panel and not the actuator? Is there a way to check the control panel signal?
Newby to this site. Did you ever come up with a way to test your control panel, i am having the same issue?
 

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2009 saab
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4 Posts
Newby to this site. Did you ever come up with a way to test your control panel, i am having the same issue?
I am also having the same issue. I replaced the actuator and re-calibrated, but the problem persists - just hot air from the driver's vents. Is there something internal to the HVAC casing that can fail? Maybe the vent blend doors themselves can fail?
 
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