[jonmaceng]

Hey guys,

Its cold out right now, so when I start my car, I have the AC set to auto, and when the car warms up and the cabin is approaching the requested temperature, it seems that the AC starts doing something to regulate the temperature, and about every 30 seconds, I will hear a hissing noise coming out of the front air vents. It lasts for about 20-30 seconds, then it is quiet for 20-30 seconds, and this process repeats in a cycle. If i shut off the front air vents (disable the air flow) or I turn the heat nob on the front vents from heating to cooling, the hissing noise goes away. I think when the hissing occurs, I hear something move mechanically behind the dash (like a vent is opening or closing).

I'm not sure where to start with this.

[bimmerchick718]

Hey, I'm experiencing the same hissing noise coming from the a/c right in the middle of the dash. I also noticed that this hissing noise came about once the temperature had dropped here in NYC, and there was no noise during summer months. I'm thinking about bringing it in to service to get checked out, I just hope I don't get the run around. I wanted to ask does your a/c temperatures seem not so cold or not so hot when set to maximum?

[jonmaceng]

Originally Posted by bimmerchick718

Hey, I'm experiencing the same hissing noise coming from the a/c right in the middle of the dash. I also noticed that this hissing noise came about once the temperature had dropped here in NYC, and there was no noise during summer months. I'm thinking about bringing it in to service to get checked out, I just hope I don't get the run around. I wanted to ask does your a/c temperatures seem not so cold or not so hot when set to maximum?

I think my ac is working fine in terms of hot and cold, it's just the hissing gets annoying after a while. And yea, I have no hissing in summer either, seems like its a winter thing...

[BMWSOZE]

Originally Posted by bimmerchick718

Hey, I'm experiencing the same hissing noise coming from the a/c right in the middle of the dash. I also noticed that this hissing noise came about once the temperature had dropped here in NYC, and there was no noise during summer months. I'm thinking about bringing it in to service to get checked out, I just hope I don't get the run around. I wanted to ask does your a/c temperatures seem not so cold or not so hot when set to maximum?

Its the black mamba of an engine we have

[mcpcolas]

It's normal it's the system switching from recirculate air from inside the cabin to outside fresh air. u can turn it off by pressing the recirculate button until that little green light disappear completely, then it's only set to outside air only

[LittleBlue]

My question is on the fresh air vents, it seems at times that they don't open to let the fresh air in automatically when the outside temps is above 40 degrees F, is there a minimumum outside temp that it needs to be at so the fresh air vents to operate normally without the A/C needing to be on? Otherwise it keeps getting hotter and hotter in the car and climate control set at 68 degrees F and the inside of the car could reach 80, any thoughts? are they sticking shut? Because when they do open I hear a flop as if the rubber flaps having trouble dissengaging from the vent walls, does that make sense? Anyone knows if this can be reached from the engine bay? when I turn the A/C on then everything works fine! but should I have to keep the A/C engaged and the compressor running even if the outside temps are at 40?

[Envuks]

Mine will whistle a little tiny bit when on defrost... It's subtile but I still notice it