Blend Door - specifically "Mode" door

[rickinAZ]

I know that there is a revitalized similar thread currently active , but I have some specific questions about the "mode" door:

I’m starting to notice the early signs of a problem—specifically a subtle plastic gear-grinding sound—coming from the glovebox area when I open the passenger door with the ignition off. As far as I know, there are three actuators in that region:

1. The rightmost actuator, next to the cabin filter housing (recirculation).
2. A second actuator about 12" to the left behind some ducting (temperature blend).
3. A third actuator located directly above the second (mode: dash/feet/defrost).

I ran the HVAC self-test with my Foxwell 510. It passed “recirc” and “heat,” but failed “defrost panel doors.” That’s their terminology, but the meaning is pretty clear.

Since I live in Phoenix, my HVAC is almost always on recirculate and set to the lowest temperature—so those actuators don’t get cycled much. I do change the air-direction settings pretty often, though, so it makes sense that the mode actuator would be the first to act up.

I tried using an automotive stethoscope to pinpoint the exact source, but the results were less definitive than I hoped.

Questions:

• Any thoughts on whether this points definitively to the mode actuator?
• Am I correct in its location?
• How difficult is replacing the mode actuator compared with the recirc and the temperature actuators?
• Am I missing any diagnostic steps that would narrow this down further?

@mwilk012 you seemed particularly knowledgable on older threads.

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[mwilk012]

I’m not sure why this didn’t send me a notification, sorry. The mode door is one of them on the center of the air distribution box, behind the glovebox. It’s the top one. 0.8 hours labor, realistically about a 10 minute job.

The noise usually comes from the recirculation door actuator. If the noise is easily repeatable, just pull the glovebox, cycle the motors back and forth and see which one chatters. I normally just put my hand on the motor as it runs and it is very clear.