This is the second issue I have with my used 2008 Durango 4.7L.

It has the higher end dual zone heater control with the Auto setting and Rear Control.

I cannot change it from Vent to anything else. Nothing at all happens when I click any of the other mode buttons, no sound, no change, only vent. Fan works great.
There is a noise and some change in temperature when I adjust the temperature all the way down to Lo and then back up. Sound like a motor gear running sound, I believe this is the blend actuator and it seems to work but is very noisy. This is the one on the very bottom of the heater box, by the fan.

Nothing from any other actuators. Would really like it to be stuck on Defrost/Floor rather than Vent, as its getting frosty outside here.

Any suggestions? Could this be the actual control, a fuse, failed actuator or the infamous broken door inside which I have to remove half the dash to fix?

 

Sounds like one of them for sure. I would bet on a bad dash control or actuator. Get in there and run some tests. Run jumper wires if you have to, but operate the system with the controls in your hand so you can see what's happening or not happening.

 

Thanks for the feedback. I found a used actuator from a wrecked 2007 Durango I am going to experiment with later. Hopefully it is not the heater control itself, but half the lights are out on the control so maybe it is bad and I have heard those lights are not easily replaced due to them being LED soldered in. I am hoping it is just a electrical trouble, as if it was a broken door, I would think there would be some noise still from the actuator.

Will update my progress as I get this figured out.

 

I had time to look at this today in greater detail finally. Just to clarify this is the mode actuator, which can be accessed from the drivers side and is up above the throttle pedal on the heater box.

Turns out the mode door actuator had been removed by the previous owner and not replaced at all, hence there was no noise from the missing actuator. I tried my used actuator but while installing noticed the attachment to the mode door was very loose. On further inspection it turns out this was indeed the broken mode door problem. To remove the broken mode door requires tearing down most of the dash to remove the entire heater/AC box, and opening it to get to the broken door. I had been quoted well over $1200 for this fix.

I just wanted defrost heat, and didn't care so much about the vent air, so I used a 1 1/2 inch hole saw to open up a small hole to see exactly where the mode door was, as it was still swinging freely. Once I could get my finger into the box to hold the door in the proper position, I put a screw through the plastic to hold the mode door in the Defrost/Heat position. Problem solved. Taped over the access hole. Total cost $0.10 in electrical tape and one screw and about an hour to figure it out and temp fix it.

I now have working Heat and Defrost, but no Vent air. The heat/cool blend and the heat/defrost actuators still work fine, so I can still adjust temperature and switch between floor and defrost.

This will get me through the winter until I can devise an easier method of replacing the broken, cheap as f**k, plastic mode door. I may use the after market metal door kit.

If your going to try this fix, I drilled my access hole, pretty much dead center between all three screw mounts, which hold the actuator motor. Then you can see and access the door and determine where to put a screw through to hold the door in the correct position. Gravity will make this mode door fall to the Vent only position, so you need to hold it in the upper position to get Defrost/Heat. Another actuator near the mode one, does the blend from Heat or Defrost. The temperature blend door is near the floor on the passenger side, by the fan.

Hope this saves someone the $1200 in the middle of winter with no Defrost.

 

That sir, is fantastic. Nice job.

 

I find that every time I loan out my 2002 Dakota it come back with something broken. This time it came back with the AC not working. I put gauges on and checked the pressure. Low was fine. High quickly got very high. I guessed that as meaning that the AC blend door is stuck closed causing the evaporator to get hot due to lack of air circulation (just a guess). I crawled under the driver side dash and removed the acurator motor and found that it works (bench test with 12 volts). Then I removed the Blend air module round rotator piece and found that a plastic tit was broken off into it (stuck in the grease) that moves a blend door. I used a piece of a nail and some JB weld to fix the tit and reassembled. It worked until I restarted the truck the following day. My guess is that there is more wrong (whatever cause the tit to break). I'm in Hawaii and don't care about heat but do care about AC so I played with manually changing the blend doors until I got AC air flowing into the cab. I'm gonna try running it that way until I find a good fix, hopefully short of pulling the dash off.