Last night, I noticed my heater making a somewhat high pitched "whirring" noise. It was fairly consistent for a while and then eventually would come and go at random intervals. Turning the fan up to the highest level didn't affect anything, nor did changing between the settings (feet, defrost, etc) and letting them run for a minute. This is the first time I've ever heard this noise. It was cold, but I always keep the heater off until the temperature gauge reaches halfway between cold and the normal reading at the "1/2" mark.

The problem happened again this morning. This time, I tried running the A/C to see if that changed anything; it didn't. I just realized that I haven't tried the "circulation" setting on the heater, so I will try that later. But, when I turned the heater off, before I turned the car off, it made a grinding noise when it usually makes an air releasing sound.

Any thoughts on what this might be?

Edit: I have a 2006 3.7L. The heat blows out just fine as well and I don't notice any odd smells or see any smoke.

Had to fix my friends wrangler that was doing something similar at one point. One of the 'doors' that controls where airflow was going to had been kicked out of it's track by a 12 year olds foot. Best I could figure was the sound was a combo of air passing by the mostly closed trap and a loose vacume hose.

Just a thought!

the trap closest to the blower will cause a pretty distinct whirring sound if it sticks, you can carefully manipulate it with your hand with a little finese to open that trap to see if the noise goes away, if it does, check to make sure all of your vacume lines under the dash for the heat/ac are snug

hopefully its something simple and free

if you plug the blower up backwards it does it too but i dont think you're having that particular problem

grinding noise, ignoring something stuck in the fan, sometimes the vacume acutators will make a popping or grinding sound if their traps are out of track, the traps sit in tracks similar to the way the fins in your ac vents are aligned and operated by a vacume plunger and metal guide lines

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03 Renegade (Black)
177k miles 3.7L gas - 45RFE
Command Trac / 4.10s
Lift: ft. 790+ rr. JBA4+
The last of the TrailReady Front&Rear Bumpers and TR Rock Rails
Jarhead Offroad light covers
31x10.5R15 RedLetter Grabbers on Blackrock Dunes
L.O.S.T #KD098632

My dad had something in one of his vehicles. I don't remember which one.
One day, his heater started making a fluttering noise. Then he found out that he started getting heat on the floor on his drivers side. {didn't before} Then about a week later, this foam rubber piece just pooped out of the newly aquired floor vent.

It seems that it was in there from the factory, and it just broke loose one day. I don't know. Maybe you have something in there that is just hanging on???

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-08 KK Bright Silver Met.
Mopar front tow hooks,
Mopar Skids
Curt class III/IV hitch, and wireing
O.K. Offroad steel reciever shackle
Zune 80 gig for the tunes,
(Do Jeep slush mats count?)
Life size Amstaff terrier bobble head in rear seat

If it's the same noise my KJ makes in the mornings, it's the bearings in the blower motor starting to die.

same blower motor theyve been using for years isn't it? dime a dozen at the yard if they are

by the way..

if you ever end up with a broken blower plug, try checking the junk yard, theres one exactly like them just backwards in the dodge pickup truck front wiring harness near the drivers side headlight bundle, all you have to do is wire it backwards otherwise your blower spins backwards

(in reference specifically to 04 wrangler, perhaps similar on other jeep models)

_________________
03 Renegade (Black)
177k miles 3.7L gas - 45RFE
Command Trac / 4.10s
Lift: ft. 790+ rr. JBA4+
The last of the TrailReady Front&Rear Bumpers and TR Rock Rails
Jarhead Offroad light covers
31x10.5R15 RedLetter Grabbers on Blackrock Dunes
L.O.S.T #KD098632