humming after engine is off.

[spieluhr]

hey, after i turn off my engine i hear a constant humming noise that sounds to be coming from the A/C. Is this something i need to worry about? Can i fix it easily? any suggestions are more than welcome.

thanks

[TECH]

http://www.bmw-forums.com/forum/inde...showtopic=8440

Does the noise go away after a few seconds?

[spieluhr]

i dont stay in the car long enough for it to stop. so it takes a few minutes from what i gather

[Furious]

mine does the same thing, i dunno if its the vent fan still running or something.

[frank3]

Don't know if it's coincidental, or related...but my noise goes away when the interior lights go off a few seconds after you take out the key. I always thought it was some sort of capisitor or relay noise.

[Morpheous]

Oh dont u just love beemers and the noises that they make?

In the cold I used to notice the climate control would make a "click-clunk" noise from the console where the transmission selector is. Apparantly its a release valve that gets rid of excess hot air or something.

The noise you're talking about, the gradually decreasing "Hhhhhmmmmmmmmmm" noise is from the climate control system. When you press the buttons on your climate control (Air for top, air for front, air for the footwells) u will hear similar sounds. My guess is that when the engine is turned off, the climate control system shuts down the outside air or closes the vents inside to prevent any air loss etc.

If you've had the air conditioning on as well, u will hear some refrigerant noises as well. Something to do with back pressure when the system is turned off.

There's another noise that comes from the dimming circuit which automatically dims the courtesy interior light. The sound is quite similar to a normal household light switch dimmer.

All these noises will disappear after a minute or so. I think they are funky!! its a unique signature for my car. Freaks everyone out esp at nite time! I love my beemer now! as sad as that sounds!