Defrost vent whistles

I just responded to the other question and asked you to get a new one posted.

Thanks for already doing that.

Can you do a test for me? Can you get the whistle to start and then press the recirc button and see if it goes away?

If it does, then this is a fresh air/recirc door issue. Also, the fact that this is only on one side and a dual zone temperature truck means we need to suspect it is one of the passenger side actuators or doors that is not sealing.

Based on what happens when we try to narrow this down, I am sure we will be able to target it.

However, the other way that may be quicker is to access the side that is making the noise and remove the actuators one at a time and manually move the door to see if it will seal. If it does, then the actuator is the issue. If not, then we have a cracked door.

https://www.2carpros.com/articles/replace-blend-door-motor

Below is the location of the actuator for the recirc but let's start with this and see what we can figure out. Thanks

Okay. So, this is most likely going to be a mode door issue.

Basically, if you are putting it in defrost and the issue stops then that means all the air is being routed to the windshield and it is not even getting to the mode door which distributes the air to the vents or floor.

So, what I would do is remove this actuator and manually move the door and turn the system on so that it makes the noise. This is going to tell us if we have an actuator issue or not.

I attached the info below for this.

Haha. Well, that does change things.

So, if this is making a noise in all settings except defrost but you have to be moving then we are going to need a little different tactic.

When you are in defrost the recirc door is closed so that you are not pulling in more fresh air.

Basically, defrost is there to pull as much moisture out of the air so that it warms/cools the windshield but blows dry air on it. This means it does not want to pull in outside air that will contain higher moisture than what has already been conditioned.

This means that I would have expected the recirc closed make a difference. So, if that makes no difference then the only thing, I can think of is that door is not fully closing except in defrost.

The way to confirm this is to use a scan tool and command the door fully closed and then see if the noise goes away.

Any chance you have a tool capable of this? I don't want to tell you to guess at the recirc door actuator but without it that is what would make the most sense.

Well, that makes me a little nervous but if this only makes the noise when you are moving then that has to be related to the recirc/fresh air door.

So based on all this, if it were me, I would replace that actuator and see what happens.

Sorry. I thought I included that before. However, I didn't give this detail. I was sure this one was, but the instructions say you have to pull the panel down.

I attached that process as well. It is more work, but it is not terrible.