My 2002 Baja has been a good car but it seems the ventilation gasket material is breaking down. What do I mean? When the heater is, I can still feel a slight bit of air leaking from the dash and defroster vents. Like the foam rubber gasket material around these flaps is breaking down causing leaks. 

Not too big of a deal as long as the heater and A/C still work but I guess from years of having to manually open and close the dash vent on the driver's side has caused an annoying side effect. When the heater is on and this vent is closed, it creates an annoying whistle. The one on the passenger side does not do this because it's seldom opened/closed.

I can manipulate the tone of the whistle by opening the vent. Eventually I find a sweet spot to where the whistle goes away. I just point the vent toward the window.

I'm wondering if the insulation has come loose or can be replaced. This whistle does not occur on defrost mode. Just when the heater is on. Not sure about the AC because I always keep this vent open anyway.

Can this vent be popped out without having to remove the dash or instrument cluster? Before I start prying on it with a screwdriver?

 

I know on my 03 Forester those vents just snap out.  I use a plastic pry tool (Harbor Freight special) 

You can go here and download a shop manual for your car and verify if it shows how to get them out.  https://sl-i.net/FORUM/showthread.php?18087-Subaru-Factory-Service-Manuals-