Whistling noise from HVAC system...

I have a whistling noise that is consistent with the fan speed for the blower motor. The noise is coming from behind the dash on the passenger side. Ive already had the TSB done and this is NOT the chirping.

Its a straight whistle. it goes away if I open a door, roll a window down, or remove the particulate filter. I ordered a filter from rock auto today in case that's the culprit, but didn't know if you all had any other suggestions?

Thanks

 

Well since it goes away when you open a door (or window?), I'd it might be related to the pressure in the vehicle when the fan is on. One thought, Is it possible you have a tiny hole in the area leading to the outside (i.e. firewall or floor under the dash possibly from a missing screw or access hole/missing plug)? IT may be whistling as the pressure pushes the air outside the car?? I'd also check the blower housing for the same...

 

it has to be pressure related as u said. i attributed it to a dirty filter since it goes away when the filter is removed.

 

Leaf or something caught in the area with the filter and whistling as the air goes past it?

 

Check you cabin filter cover sounds like it wasn't installed correctly or came a little loose I have seen that a few times