I have an 02 Tahoe and an 03 Avalanche, both let cold air in on the passenger side under the glove box in the winter as you drive down the road. It's bad enough that the wife won't ride in the front seat...what the heck is going on??

 

Perhaps the actuator motor isn't working.

 

I have the same problem, haven't done anything with it yet, but did research these links.

Tom

SilveradoSierra.com ? Cold air into passenger side wife's feet freezing! : Interior

http://ww2.justanswer.com/uploads/Bl..._passenger.pdf

https://www.google.com/search?q=2001...utf-8&oe=utf-8

Cold air coming in on passenger side??? - TheDieselPage.com Forums

 

I'll look on my computer when I get home from work. If I recall, I had a similar problem with my 2002 Tahoe, it's been years. But I do remember there were 2 issues, one being due to an incorrectly routed wiring harness that would cause excessive pulling on a connector on the heater control module and make strange things happen. The second was the dealer replaced the heater control module that contained updated code/programming to make it operate differently. I guess they could not flash these old modules with updates.

 

Sorry for the delay, but it's been nutty at work and it took longer than expected to find those old bulletins on my computer.

https://chevroletforum.com/forum/att...1&d=1517969185

https://chevroletforum.com/forum/att...1&d=1517969185

hopefully this will help you out on your loss of heat problem. I know it did on mine. What had me wondering if it was actually the HVAC control module lockup that was causing my particular situation.