Whistling behind dash

2013 1500 5.7 2wd Express Crew Cab.
40+ mph I have a whistling sound near windshield or dash area. I taped windshield, doors, door jambs, window glass, hood, removed antennae and wipers, still have whistle. So I got my girl to ride with me and she doesn't like the ice box I keep my cab cooled to with AC....so she turned the HVAC to defrost. Whistle goes away. If I turn it to feet or face, the whistling comes back. Put it back on defrost, and the noise goes away again. I don't have any blend doors clicking or popping, no other sounds in the cab. I've heard nightmares from other guys on here talking about road noise, wind noise etc, but I have had no noises except for this whistling that goes away with the defroster on.

Oh btw...it doesn't matter what position the fan motor is in, full blast or off, or in the one or two spot, it still makes the noise as long as it's not in the defrost position...

Does it still whistle when you put it in recirculate on any function other than defrost?

Yes. Recirc or not it still whistles.

Also the faster I go, the louder it whistles. But does NOT change with RPM's...

One of your buddies put this in your dash



On a side note, I'm actually thinking about stocking up on a few of these to put on some coworkers trucks.

https://youtu.be/WYvvLB4b6Ag

Still sounds like it has something to do with the recirc door because in defrost it forces the recirc door closed so it draws in outside air. I know if I'm going down the highway and I switch from outside to recirculate it whistles for a second as it door moves. If you pull the glove box out you can see the recirc door moving and verify its fully opening and closing.

Try taking the wipers/cowl off and take a look at where the outside air intake is on the passenger side. Might be something as simple as some leaves or something in there....

Hemi395 said:

Still sounds like it has something to do with the recirc door because in defrost it forces the recirc door closed so it draws in outside air. I know if I'm going down the highway and I switch from outside to recirculate it whistles for a second as it door moves. If you pull the glove box out you can see the recirc door moving and verify its fully opening and closing.

Try taking the wipers/cowl off and take a look at where the outside air intake is on the passenger side. Might be something as simple as some leaves or something in there....

Click to expand...

I agree

Hemi395 said:

Still sounds like it has something to do with the recirc door because in defrost it forces the recirc door closed so it draws in outside air.

Click to expand...

I think we're talking about the same thing, but doesn't the recirculation door "open" when you turn on defrost? If it's "closed" it shuts off outside air...

Either way, I agree it probably has something to do with the recirculation door...I did the cabin air filter mod, but it made noise the same before the mod so I knew that didn't have anything to do with it. I think I will pull the cowl though, the truck was bought new in Texas, and lived it's life there till I got it a couple months ago. I'm in upstate SC now. The truck wasnt detailed very well and had massive amounts of dust in crevices etc etc... It might have clogged up around the recirculation door inlet now that you mention it. I'll be sure to update this thread for other members in the future if I find it.

And Austin, I don't have any friends so I'm sure that's not my problem. You can go back to making fun of the lifted two wheel drive trucks and posting *** crap now, thanks for the contribution to help solve my problem though.