Loud Popping Sound when Turning on Heat/AC

[MirrorrorriM]

Whenever I hit the 'Up' arrow on the center console to turn on the fans, I hear a loud audible pop from the center ventilation area of the car. It only happens once and you don't hear it again until you turn the fans off and back on again. Otherwise, heat and AC both work just fine.

[Abby77]

sounds to me like there is something on the seal of the flaps that control where the heat or ac goes to and it might be sticking and making the pop sound you are hearing



Edit

Or could be the gears that open it up are stripped ?

[clumsyculhane]

Mine does this too, after about 10 mins after turning the car on (i.e. when its warmed up), a noticeable clap can be heard from the HVAC area. Everything works fine, and it only makes the sound once per day or less.. I think its probably just a flap opening that maybe has a slightly stuck actuator, so that it initially can't open but then overcomes whatever is stopping it, then it snaps open/shut, or maybe some insulation has disappeared on the edges that it touches. This is of course pure speculation, but it seems fairly benign.

[slocar]

My dad's 318i does that .. and has been for the 2 years he's had it without other issues.

[Kody]

Mine does it too its just the vent door opening

[MirrorrorriM]

Thanks guys. Yeah it doesn't bother me enough to fix it, but it usually makes my passengers jump when they hear it. I'll leave it alone until I have a reason to get in there.

[HamsM5]

I was searching and ran into this thread. My car literally just started doing this. Quite annoying as it is alarming to hear. While everything is operational, it does concern me that it will get worse as time passes. Any thoughts on how involved it is to fix?

[slocar]

I am happy to report my newly acquired 323 also does this after a while.

[beegeezy]

My car does this also. I may do some digging around the airbox to see if I can find which doors are sticking...maybe a little silicone spray will help.

[HamsM5]

I just replaced my center vent and this started up about a week later. I wonder if the cold/warm mixture bowden cable has something to do with it

[beegeezy]

My car made the noise prior to replacing the center vent and still does now after replacement.

[Chapel]

mine does this too.

[c0lin46and2]

Mine does this too when I change the air settings.

[Bacender]

My E36 did the same thing for 3~ years. The flaps are opening up to let the air through and it tends to stick when the car has been idle for a few hours (over night). Mine only ever used to do it once a day.

Don't stress too much.

[AzNdevil]

mine does it everytime i turn the hvac on and off....been doing it for the past year but everything else is functioning properly...

[blackongrey]

Must be nice to have passengers.

[MirrorrorriM]

Must be nice to have passengers.

Ask bacender if you can borrow his avatar.

[slocar]

http://1.bp.blogspot.com/-bYwcmlMxsXU/UA_ugRxYU2I/AAAAAAAAEVw/VzWvf9ucU8M/s1600/forever-alone-face.png

[Ckyo5]

My middle vent option does this... I just keep the mid-level selection off and no scary noises to deal with.

It used to open after the car warmed up.. so 15 mins into the drive... POP!! Used to scare the shit outta me:eek:

[slocar]

My middle vent option does this... I just keep the mid-level selection off and no scary noises to deal with.

It used to open after the car warmed up.. so 15 mins into the drive... POP!! Used to scare the shit outta me:eek:

Mine does it if the system is set to auto. I guess you just keep yours selected for the floor level only?

[gilliemar]

i get the same exact thing, it scares my new passangers

[Ckyo5]

Mine does it if the system is set to auto. I guess you just keep yours selected for the floor level only?

Correct...I don't like weird smelling air on my face anyways lol.. I've slipped up and hit auto a few times..a few mins later... :eek::eek:.....:rofl

[slocar]

Correct...I don't like weird smelling air on my face anyways lol.. I've slipped up and hit auto a few times..a few mins later... :eek::eek:.....:rofl

Mine doesn't do that. Actually on auto, it hardly even blows anything out of the center vents ... for the most part it's blowing out of the footwells. Actually I don't get any weird smells even with it set to just face.

[JDStrickland]

I never ever not even once turn the fan off.

I put the fan speed to 1, or higher, and never change it. I don't hear the banging and clanging of flaps and stuff that you hear.

[Ckyo5]

Actually I don't get any weird smells even with it set to just face.

Its probably just weird cuz I never let air through that passage anymore? Its not a mildew smell... just, a old air smell:shifty


I never ever not even once turn the fan off.

I put the fan speed to 1, or higher, and never change it. I don't hear the banging and clanging of flaps and stuff that you hear.

Yours doesn't do it then....yet. When you turn your car off, the flaps close every time. You can hear them if you're paying attention.

[JDStrickland]

Its probably just weird cuz I never let air through that passage anymore? Its not a mildew smell... just, a old air smell:shifty



Yours doesn't do it then....yet. When you turn your car off, the flaps close every time. You can hear them if you're paying attention.
On my other E36, I could hear a soft noise that I always thought was the flaps moving around. It sounded sorta like pulling the tab on a soda can, kinda. Does the OP have this sound, but the foam rubber on the flaps is missing, so they make more than the soft thud that mine made?