[hemixav3000]

This morning, I tried to get the vent on Defrost. I can feel the air starting to come out of the defrosting vents and then I hear a fairly loud "pop" noise and all the vent is redirected to the front vents.

Obviously something to do with the defrost door, but what ?

I have read a lot of posts about people loosing the defrost alltogether, mine is slightly different though.

Have you guys seen that before ?

Maybe it's just on its way out ...

I just don't want to have to pull the whole instrument panel out ...

 

[antman182]

ive seen it too

infact i hear it everytime i start my truck and turn the fans on (only happens when the truck isnt up to operating temps)

i thought it was the tranny at first but traced it back to the vents. i also noticed that i dont get any cold AC out of the passanger side vents. driver side is fine though.

im planning on taking this issue to the dealer when i get an opportunity.

ive told them about the banging sound when i first put the fans on but they couldnt repllicate it so they couldnt do anything

 

[hemixav3000]

Well, I had heard the "pop" before, but the vents never did this weird thing where they start going to defrost and then switch right back to the front vents ...

It takes about 2-3 seconds to start feeling the air in the defrost section and then less than one to go back full blast to the front vents, right when the pop noise happens ... like the door is slamming back ...

 

[piper18]

Sounds like it the old broken flapper door problem, very common but very $$$$ if you have the dealer do it, you have to rip out the dash to get the HVAC box out to open it up.

 

[Noved]

Mine does it too. Glad I am not the only one.

 

[MikeyB]

Two things to try in preventing the blend door from breaking. Before switching modes turn down the blower to low speed or off, two turn the mode knob slowly, so the servo motor doesn't drive the door past the stops. I haven't broke mine yet (knock on wood).

MikeyB

 

[the_transporter]

Mine does it, so did my 06. I wouldn't call mine a "pop" but more of a "clunk"...lol

 

[RB24]

same here on my 07