2000 Tahoe inside/outside air door goes bump bump bump

[Randy Whistler]

Ever since we had the polar plunge here in Kansas a few weeks ago, there's been a bump/bump/bump/bump regular tapping coming from the passenger side under the dash. It took a while to reason out what was happening, but I think I've got the location and parts figured out, I just don't know which is what. It's sometimes intermittent, so it's hard to chase down. Today it quit bumping but it'll be back, I'm sure.

When the fan switch is off, the bumping happens regardless of where the selector switch is at.
With fan on, selector switch in any position, heat/cold switch any position, outside air selected, bump/bump.
With fan on, selector any, heat any, INSIDE air selected, no bump/bump/bump.

This leads me to believe that the problem is with the actuator/door that controls outside/inside air intake. The noise comes from behind the glove compartment on the passenger side. I had the dash cover off this weekend to fix my daytime driving light sensor, but wasn't able to get down deep enough to make any useful discoveries.

I've searched both YouTube and this forum, but without knowing exactly what to ask, the results were mixed. I am looking for what parts are needed, and a little advice wouldn't hurt, either!

As always, thanks for any and all advice/help in advance!

 

[Randy Whistler]

Hmmmm - interesting

 

[Fless]

A good bidirectional scanner should be able to test and verify the actuators, commanded position vs. actual, to determine which one(s) are acting up. A Tech 2 would do this for you.

 

[Randy Whistler]

A good bidirectional scanner should be able to test and verify the actuators, commanded position vs. actual, to determine which one(s) are acting up. A Tech 2 would do this for you.

Thanks! Will look into that!

 

[JonnyTahoe]

You didn't need to remove the dash cover. You can get to the sensor by removing the radio it's right behind it. While you had the dash cover off that was the perfect time to replace the fresh air door actuator.

 

[Randy Whistler]

You didn't need to remove the dash cover. You can get to the sensor by removing the radio it's right behind it. While you had the dash cover off that was the perfect time to replace the fresh air door actuator.

That was why I took the dash pad off, thinking I could get to the actuator, but once I got it off, I didn't know what I was looking for or where it was. Does it live behind the airbag or the glove box? I thought maybe I needed to remove the airbag, or maybe the cover under the dash(where the air filter lives), but once I got in there, i realized I didn't know what I was doing and stopped before I tore something up. I also didn't know about a "sensor" behind the radio. Stupid questions, probably, but what does the sensor do(other than sense something )? The actuator I sorta understand . . . .

Forgive my ignorance, but the GM line is still a bit of a mystery to me. I come from FoMoCo/Mopar/VW but the way GM does things is totally different than I'm used to. I'm more familiar with the vacuum pot/lever operation than the way this is done. Everything else I've done on the Tahoe so far has been fairly simple once I understood what to look for or where it was, and I'm hoping the same will apply for this, just need some education. . .

 

[JonnyTahoe]

That was why I took the dash pad off, thinking I could get to the actuator, but once I got it off, I didn't know what I was looking for or where it was. Does it live behind the airbag or the glove box? I thought maybe I needed to remove the airbag, or maybe the cover under the dash(where the air filter lives), but once I got in there, i realized I didn't know what I was doing and stopped before I tore something up. I also didn't know about a "sensor" behind the radio. Stupid questions, probably, but what does the sensor do(other than sense something )? The actuator I sorta understand . . . .

Forgive my ignorance, but the GM line is still a bit of a mystery to me. I come from FoMoCo/Mopar/VW but the way GM does things is totally different than I'm used to. I'm more familiar with the vacuum pot/lever operation than the way this is done. Everything else I've done on the Tahoe so far has been fairly simple once I understood what to look for or where it was, and I'm hoping the same will apply for this, just need some education. . .

Go to any auto store website and look-up actuator in Hvac section will look something like this.

 

[JonnyTahoe]

Here is the Fresh Air Actuator. I spent over an hour removing stuff so you and everybody else can see where it is. I also removed all the Plastic vent tubes that run over the top of the actuator making it very hard to see let alone remove. I removed the Airbag and a bunch of plastic so you can get a real good look at it. You need to remove a lot more than just the dash cover there is a lot of structure that I removed as well.

 

[Randy Whistler]

Wow, that helps a lot, thank you for providing this! This is going to require some serious study but the pictures will be invaluable! Thanks again for taking the time to take and post these!!

 

[JonnyTahoe]

Wow, that helps a lot, thank you for providing this! This is going to require some serious study but the pictures will be invaluable! Thanks again for taking the time to take and post these!!

Do Not remove the Airbag !!