Rear A/C Blend Door Actuator.

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swantzilla
Posts: 4
Joined: Sun Apr 26, 2009 4:09 am

Rear A/C Blend Door Actuator.

Postby swantzilla » Thu Feb 25, 2021 10:01 am

Hello,
I replaced the rear blend door actuator on my 2009 Armada for ticking. I fired up the rear A/C and noticed the ticking was gone but it was not changing the air from floor to ceiling. I hooked up the old actuator and watched the white shaft and it was not turning. So the ticking is gone but it is not changing the rear airflow. Any ideas?


swantzilla
Posts: 4
Joined: Sun Apr 26, 2009 4:09 am

Re: Rear A/C Blend Door Actuator.

Postby swantzilla » Thu Feb 25, 2021 12:06 pm

Update, Removed the new blend door actuator and watched it just electrically connected. It does indeed rotate. But it only rotates in one direction, it does not reverse.

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VStar650CL
Posts: 2716
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Car: 2013 Nissan Altima 2.5 SL
2004 Nissan Altima 2.5 S

Re: Rear A/C Blend Door Actuator.

Postby VStar650CL » Thu Feb 25, 2021 12:11 pm

There's a separate mode servo back there that changes floor/ceiling, the mix door only controls outlet temp. In most cases the way Nissan auto air systems work, the rear system blows heat to the floor-only and cold to the roof-only. Thus, if it's on a cold setting there will usually be roof flow right away, but on a heat setting there's often no flow until the vehicle warms up. If there's an issue with both servos not moving under any conditions, then you may have a global problem with the power, wiring, or rear control.

swantzilla
Posts: 4
Joined: Sun Apr 26, 2009 4:09 am

Re: Rear A/C Blend Door Actuator.

Postby swantzilla » Thu Feb 25, 2021 12:49 pm

On my Armada, I can select where the rear air will come out of, either the floor or the ceiling. Watching the new actuator, when I select the floor, it rotates, when I select the ceiling, it rotates but in the same direction. If the unit was installed, it would jam the door in one position, maybe that is why the first one broke. I have seen people call this a blend door actuator but is seems like it should be called an air diverter door. It may be that the controller does not know where the position of the actuator is and needs to be reset?

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VStar650CL
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Car: 2013 Nissan Altima 2.5 SL
2004 Nissan Altima 2.5 S

Re: Rear A/C Blend Door Actuator.

Postby VStar650CL » Thu Feb 25, 2021 1:53 pm

swantzilla wrote:
Thu Feb 25, 2021 12:49 pm
I have seen people call this a blend door actuator but is seems like it should be called an air diverter door. It may be that the controller does not know where the position of the actuator is and needs to be reset?
The right name is a Mode Door, it controls where the air goes. The Blend/Mix door is a whole different animal, it controls the outlet temperature. You're scrambling your terminology.

swantzilla
Posts: 4
Joined: Sun Apr 26, 2009 4:09 am

Re: Rear A/C Blend Door Actuator.

Postby swantzilla » Thu Feb 25, 2021 7:24 pm

VStar650CL wrote:
Thu Feb 25, 2021 1:53 pm
swantzilla wrote:
Thu Feb 25, 2021 12:49 pm
I have seen people call this a blend door actuator but is seems like it should be called an air diverter door. It may be that the controller does not know where the position of the actuator is and needs to be reset?
The right name is a Mode Door, it controls where the air goes. The Blend/Mix door is a whole different animal, it controls the outlet temperature. You're scrambling your terminology.
You are absolutely correct, I stand corrected...But you got me thinking,,,

It is now working. My misunderstanding of how this worked led me into the woods. Thank you VStar, I am much smarter now. The Blend Door Actuator controls the blend of hot and cold( go figure) not what outlets the air is coming from. That is done by another actuator. Seems like the Blend Door Actuator needs to run the motor till the door hits the end of travel to have it figure out where it is at. No wonder there are so many broken gears. Now I may soon need to find the air flow diverter actuator as I hear an occasional tic when I change the air outlets. Thank you for all your help.

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VStar650CL
Posts: 2716
Joined: Thu Nov 12, 2020 1:25 pm
Car: 2013 Nissan Altima 2.5 SL
2004 Nissan Altima 2.5 S

Re: Rear A/C Blend Door Actuator.

Postby VStar650CL » Fri Feb 26, 2021 5:24 am

swantzilla wrote:
Thu Feb 25, 2021 7:24 pm
Seems like the Blend Door Actuator needs to run the motor till the door hits the end of travel to have it figure out where it is at. No wonder there are so many broken gears. Now I may soon need to find the air flow diverter actuator as I hear an occasional tic when I change the air outlets. Thank you for all your help.
You're most welcome! Yes, in many of the modern systems the servos self-calibrate. When an electric motor stalls the current shoots up, so as long as the doors are healthy, the actuator can locate its own travel limits by watching the current flowing through the motor. In some vehicles like the gen2 Rogue the actuators are actually plain stepper motors and not servos, and the system has to be put through a "learn" algorithm in order to work right.


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