On my '07 335i coupe, even when my heat/AC/fan are all turned completely off, there is still a noise that sounds like a small fan spinning. What is this noise? It's not always there, but probably 80% of the time, when the HVAC is completely off. I would like to not have that noise anymore, albeit a pretty quiet one. Thanks for any info/ideas.
I would like to help. Could you tell me more about this noise. Does it happen when you 1st start the car and/or after you turn off the HVAC (Heat and/or AC)? Does it happen more at certain time of the day, particular outside temperature and/or short vs long drive cycles?
Thanks for the reply. I haven't noticed any rhyme or reason to it yet, in terms of time of day, ambient temp, etc., but I'll pay more attention over the next couple of days and see if I notice any trends, then I'll report back.
Thanks, I will be looking forward to hearing your report. How soon after you purchased your 335 did you notice this noise?
Do you have Nav system? It seems to me that the noise might be coming from the Nav's DVD player and triciking you to beleive that it is coming from the heat/AC fan. Try to listen carefully, see if it is DVD. This is only if you have Nav of course.
I do not have Nav. Someone suggested to me that there is a small fan that draws in cabin air to test its temperature. That seemed like a possible answer, but why would it be testing the interior temperature if the heater/AC are both off anyway? Anyone else aware of this termperature testing fan?
Yes, this could be your problem. There is a small fan that pulls interior air temperature over a sensor to adjust Automatic air temperature feature on your HVAC control head unit.
Yes, and you will also hear noises from the HVAC when you turn the car off after a minute or two. You will various doors open or close with the sound of the motor. The system is never fully off.
Hmm, that's frustrating. Maybe I can set up a switch to interrupt the power to the system when I just want perfect peace and quiet. Thanks for the info.
I've heard it's a fan to cool the ECU, similar to a computer fan. Think of how hot that part must get with all the calculations, and computations it has to do while the car is on and off. I hear the same noise in my 08 E90 as well. Don't be alarmed it's normal.
HVAC makes noise (and then stops heating) My 2000 E46 HVAC starts up normally, however after 30 to 40 minutes it quits putting out warm air and blows ambient temp air. the engine temp gauge does not change, so i think there must be a sensor somewhere that tells it to stop heating the air. The heater is not an optional assessory in Washington State this time of year. Thank you.
