Re: whirring in the morning, haunted??

["Jim Cash" <j.cash@xxxxxxxxxxxx>]

Mark asks


I've a 1997 528i (E39) which has recently begun whirring at me in the
morning. Car resides in the garage overnight. In the am it greets me with
a whirring sound coming from the dashboard. Sounds just like the heater
blower motor set at a very low setting. Stops after 10 or so minutes of
driving. What the devil is it? Easy fix?

If that sound is coming from he climate control (behind the small left
grill) then it is the small vent fan that pulls air across the cabin temp
sensor.
That fan runs all the time the car's cabin computer network is awake (as
soon as you open a door till 16 minutes after power down and NO further
activity).
Those fans have been known to go a bit noisy. They are inside and you have
to pull the unit and open it up (split the front and back halves to expose
the fan - mounted on a circuit board on the rear half.

It is possible to lubricate the shaft - but all experience (including mine)
is that does not last for very long.
There is a fan replacement kit.

If the sound is not there then there are 2 other possibilities.

- - if you car is an automatic (not by your designation) then there is a small
blower in the electronics box  (under the micro filter in the engine
compartment on the passenger side). That blower pulls cooler air from the
cabin to help cool the electronics in the E-box. This should only activate
if the engine compartment is over 30C and the ignition is on.

- - another known fault is the final controller stage for the main blower. If
that fails then the blower can fail, stick on full speed, become erratic, or
in my case it would run occasionally at a very slow speed with the car
totally shut off - actually starting and stopping every few seconds.

I think you need to do some further investigation to see which is causing
the sound.

Cheers
Jim Cash
London, Ontario, Canada

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