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 !!

 

[Randy Whistler]

My pleasure. Do Not remove your Airbag !! View attachment 275611 View attachment 275612 You won't have too.

Thanks again!!!!

 

[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!!

Not sure how you got your dash cover off but I had to watch a few video's because it was really stuck on there.

 

[JonnyTahoe]

Thanks again!!!!

Look up that P/N in that close-up picture and try to find one like it if you can. These trucks have four Actuators and they are not all the same. Good Luck.

 

[Randy Whistler]

Not sure how you got your dash cover off but I had to watch a few video's because it was really stuck on there. Be careful they are really easy to crack.

Well, it took a lot of cussing, to be honest. I too watched a bunch of videos and when I felt brave enough, I jumped in. The first time I pulled it was to fix the PRND21 indicator on the instrument cluster, but I don't recall if I pulled the cover completely or just tipped it up out of the way. This last time, I had a particular fight with the grab bar over the glove box. First time it was a piece of cake, but apparently somewhere along the line something got bound up in the sockets and I had to really be inventive(both with removal and with colorful language) to finally get the bar out. I noticed this time that the same thing happened when replacing the bar, but I'm prepared for it now. Won't enjoy it, but expect it and not being surprised can mean an awful lot!!

Thanks again for the pix, they're really excellent and should help a great deal! This might be something worth documenting if it would help others along the way. Need to think about that. . . .

 

[Randy Whistler]

Look up that P/N in that close-up picture and try to find one like it if you can. These trucks have four Actuators and they are Not all the same. Good Luck.

I already did, thanks!! Got it on order so next time I get crazy I'll be ready for bear!

 

[JonnyTahoe]

I already did, thanks!! Got it on order so next time I get crazy I'll be ready for bear!

Where did you order it from ? You could just Disconnect it but you might as well fix it as long as your in there. I went half the winter with a disconnected Mode Door till I finally fixed it. OH Do Not Test it first just install it and plug it in. I made the mistake of testing it first even know it was new (GM) and they can rotate to far and will have to be re-calibrated. Just Plug and Play.

 

[JonnyTahoe]

Well, it took a lot of cussing, to be honest. I too watched a bunch of videos and when I felt brave enough, I jumped in. The first time I pulled it was to fix the PRND21 indicator on the instrument cluster, but I don't recall if I pulled the cover completely or just tipped it up out of the way. This last time, I had a particular fight with the grab bar over the glove box. First time it was a piece of cake, but apparently somewhere along the line something got bound up in the sockets and I had to really be inventive(both with removal and with colorful language) to finally get the bar out. I noticed this time that the same thing happened when replacing the bar, but I'm prepared for it now. Won't enjoy it, but expect it and not being surprised can mean an awful lot!!

Thanks again for the pix, they're really excellent and should help a great deal! This might be something worth documenting if it would help others along the way. Need to think about that. . . .

Yes the Grab Bar even watched a video but I thought you push that white plastic pin up and like you had a heck of a time until I looked at it close with a flashlite and figured out you push it to the side not up.

 

[Randy Whistler]

Where did you order it from ? You could just Disconnect it but you might as well fix it as long as your in there. I went half the winter with a disconnected Mode Door till I finally fixed it. OH Do Not Test it first just install it and plug it in. I made the mistake of testing it first even know it was new (GM) and they can rotate to far and will have to be re-calibrated. Just Plug and Play.

Sorry for the late reply! I ordered it from carpartswholesale.com. I've done a lot of business with them over the years so ordered from the. It was here in a couple of days.

 

[Randy Whistler]

UPDATE - I FIXED IT!!!! It wasn't pretty or simple but thanks to JonnyTahoe's pictures, its done and working! I've been a technician all my life and have had to put things in a lot of places others said was impossible so I've never been afraid to rip stuff up, and thats kinda what I did what I did.

After some significant and very serious language, I could not figure out how to get to it from below. I finally decided the Hell with it, and got out the vibra-saw. Once I removed the u-shaped metal bracket, I sawed the black tube in half. That gave me enough room to get into the 2 screws. FWIW, my Tahoe only had 2 screws so that was a lucky break. Getting the old one out wasn't simple but it came out. Putting the new one back in required a lot of the aforementioned language, but back it went. A little duct tape and reassembly, and another actuator replaced!

Thanks again to Jonnytahoe and everyone else who offered ideas and encouragement! This place is the best!

 

[JonnyTahoe]

Glad to hear you got that Actuator fixed.