I also get similar sounds coming from behind the dash/climate control when the engine is running and not running (key must be in though). The sounds occur even when the climate control is off! Sounds like moving parts or gears adjusting themselves.
I've heard mention of an air distribution cam. Does anyone know anything about that part? Is it part of the climate control unit itself or separate? I've also seen links for do it yourself climate control repair...could that be a fix for these noises?
Here is a quote from that link "Having problems with your climate control? Intermitent operation? You can fix the unit yourself for under 50p and just a little time! Armed with little more than a screwdriver and soldering iron, these units can be made fully opeartional in next to no time".
The cam is connected to the knob that controls the distribution of air between
the lower, upper and defroster vents. If you drop the glovebox, you can get to it easily. There is a part number floating around somewhere-think the part costs
about 11 bucks-which is ten bucks too much when you see the thing.
My HVAC units make those odd breathing sounds when the engine is shut down.
I suspect that it is the sound of vacuum actuators moving about when engine vacuum is lost.
E36 ac systems occassionally make a wheezing sound from the expansion valve. Replacing it may help some, but I can't guarantee that the noise will go away for good. This usually occurs while cruising down the road.
When you shut a car off, the refrigerant inside the ac system will start to equalize, going from high pressure to low pressure, and you'll hear it at times. Nothing to worry about.
Also, late model BMW's use stepper motors to move the flaps, or simply a cable that is attatched to cams and arms.
The motors return to a rest position when you turn the car off, and you'll hear that as well.
those sounds when u turn the engine off are normal i guess, like TECH says. As for the sounds that shcverp is getting aint they normal? like when u turn off the AC system i guess the air ducts are closing or adjusting or somthing i dunno.
The breathing sound i get is when the engine is on, and yeah while cruising while the AC is on, or even when im parked by the engine is on, i notice a very low breathing sound somewhere from the left side of the engine (am not that engine expert to tell u where from exactly hehe ) but yeah some kind of a recurrent breathing sound from there. i think its normal but i have to check that next time am @ the service center