HELP...LOUD whistling/humming from air ducts
 

Been noticing (on and off) that when I turn the A/C or heat on and put the blower anywhere from 50-100% power that there is a LOUD and fairly high pitched whistling or humming noise coming from what sounds like the glovebox.

If I turn the blower down, it goes away but will come right back if I turn it back up. The onset has been sporadic, but increasing in regularity. It's super obnoxious too. Any ideas?

do you have any of the dash vents closed?

if you are running the system on floor or defrost, the blower is pushing a LOT of static pressure through the system and will whistle a bit on high fan (in my 2013)..

if using dash vents. if I have nay of them closed, it will do the same.. our blowers are very strong and need all of the vents open...

-Christopher

JeepaRoo, It does it either way. Yes, it is significantly louder when some vents are closed, but traditionally I keep it on upper and lower vents usually with them all open or maybe 1 closed. it almost sounds like a piece of tape or rubber flapping really hard in a duct...is that possible?

it could be that a duct seal came loose and is dangling in the duct.. I havent torn apart the HVAC on the later JK's yet (though I need to for relo the evaporator sensor). but most cars have rubber seals between various pieces of the HVAC ducting system.. and if one of those wasnt put together correctly it could make a wierd sound..
-Christopher

Sounds like a lot of work, I may try tearing the dash/HVAC apart this weekend. Hopefully it won't cause any additional problems.