I have the Blend Door Actuator issue on the passenger side of my 2011 Durango Crew. The heat and AC are not functioning. After searching online about this issue I decided to tackle it myself. I suspected the blend actuator gear is broken and I ordered a set online. I did not find a service manual that lists the steps to replace this gear but I found a link that lists the steps in a post on another forum. I took off the glovebox and carpeted piece underneath the glovebox to gain access. I could see the actuator gear box on the left side of the glovebox behind the center console instrument panel. Next I removed the hvac vent duct that hung down behind the glovebox. Next I removed the two screws that fasten the blend actuator to the blend door duct and removed the actuator.

Holding the actuator in my hand I could see clearly that the gear was broken. Just like the pictures I saw in other posts.
So I started to install the new gear. I removed the broken one from the actuator and replaced it with the new one. When I tried to reinstall the blend door actuator, I was having trouble because the actuator gear was not lining up with the blend door gear. In an attempt to line up the gears I first tried moving the blend door gear but its movement is limited to about 90 degrees or so and it was not enough. So I tried turning the actuator gear by hand but since it is attached to a motor, it would not turn. So I had the idea to turn on power to see if the actuator would initialize to its home position. When I turned on power, at first I was happy to see the actuator motor turning slowly. I was thinking that it is now initializing to its home position. However, I was soon disappointed because the actuator motor continued turning slowly in one direction for multiple (about 2-3) revolutions. I think this is not right and I suspect it is the reason that the actuator gear broke. The blend door gear moves freely by hand but it only moves back and forth somewhere between 60-90 degrees. I suspect that the actuator motor is supposed to move only back and forth in a limited range about 60-90 degrees and the fact that it is rotating full revolutions indicates that it is malfunctioning and needs to be replaced.

I there anyone out there that can confirm my suspicion?

I am not able to post a 350 MB video (*.mov) that shows the motor rotation issue. Otherwise you would be able to see it.


Blend door actuator with new gear

Blend door gear

Blend door actuator with broken gear

 

I posted this same question on another Dodge forum. I got an answer on that one. It turns out the blend door actuator self calibrates. Below is a quote from that thread:

The actuators calibrate by feedback from when the blend door hits it's physical stops on each end of travel. The controller senses the the sharp increase in current and it makes that position the calibrated end of travel.

With you running the actuator without been installed it starts to seek the first stall point in one direction of travel. It doesn't stall so it continues to rotate. If it were physically installed it would rotate in one direction first until it stalled from the blend door hitting it's stop. Calibrate that point then reverse direction and do the same for the other end of travel.

From that information I deduced that if the blend actuator self calibrates on every power up, it will hit the mechanical stop at each end of travel putting force on the gear and causing the current to spike twice at every power up. It should be noted that once calibrated, the actuator knows were to stop to avoid force on the gear. At least until the next power up. However, over time the force on the actuator gear when hitting the mechanical stops will cause the part to fatigue and eventually fail. This is by design.

Below are links to two videos showing my investigation of this problem on my car.

Blend Door Gear

 

What were the symptoms?
I currently have an 18 with one side blowing hot air in the heat mode and cool on the driver's side.
Dodge tech says I have a clogged heater core.
I said if it was clogged, I would not have any heat in the cabin.
They said it tested it was working.
I said a test can have a false positive reading and still be bad.
Anyhow... I think this is the issue before they insist it is a heater core.
I'm not buying it... I think it is the Blend Door Actuator.

 

I am having the same issues on my 2015 Durango and I took everything apart and ran through all the settings on my hvac system and everything all the doors and stuff moved like they were supposed to that I could see. Is the blend door for driver side somewhere else? Any input would be much appreciated.