GenVibe - Community for Pontiac Vibe Enthusiasts

My 2004 Vibe started making a knocking sound from under the passenger side dashboard. When I open the hood and listen with the engine running I can't hear it. It keeps the same speed of knocking no matter what speed I drive.When I turn off the AC recirculator button it stops. I do use the recirculator fan a lot cause I park in the sun and it helps cool things down quickly when I first get in the car. I can have just the AC on (without the recirculator) and it does not make the noise. What do you think would cause that? Has it happened to your Vibe?My guesses are 1.the blower motor, 2. compressor might be leaking refrigerant/freon.3. Expansion control device at evaporator inlet TXV valve part 52845.4. Serpentine belt.5. Other ideas?I got these ideas from a discussion on GenVibe back in 2006 but wondered if anybody has dealt with this more recently. I have an appt. to see my Mechanic Friday morning/tomorrow.

Sounds a lot like this...http://forums.genvibe.com/zerothread?id=24332It's not difficult to fix, but it does take some time...

Thanks so much that was very helpful!!!

RESOLVED: So my mechanic says it was the recirculator door activator (part #88970277 $86.00 + labor). He showed me how the one he removed has plastic gears inside and some of the teeth on the plastic gear broke off so the gear did not turn smoothly anymore so when it got to the broken teeth it would get stuck and then "snap" across and that is what made the knocking noise under the dashboard. Of course you can't just replace the damaged gear but have to replace the whole thing. I took some pictures and will add those later.http://i278.photobucket.com/al...2.jpg

Quote, originally posted by Blueridge9 »RESOLVED: So my mechanic says it was the recirculator door activator (part #88970277 $86.00 + labor). He showed me how the one he removed has plastic gears inside and some of the teeth on the plastic gear broke off so the gear did not turn smoothly anymore so when it got to the broken teeth it would get stuck and then "snap" across and that is what made the knocking noise under the dashboard.Looks kinda sorta exactly like this, right?That's what others have run into, but whether its the limit switch or the gears, its all the same part.Glad you got it fixed...

Yes that's it exactly. Too bad those gears are PLASTIC. If they were metal maybe they would last longer. While they had the dash open we changed the cabin air filter too.