Intermittent whining noise from behind the pod
 

On a cold morning and again in a chilly afternoon, my 1988 928S4 manual began to make several short periods of a high pitched whining noise from behind the gauges in the pod. This did not seem linked to speed or RPM's, it would start then stop several times while driving. It went away after less than a minute of driving. All gauges are working normally. ODO working normally. No work in the dash at all in the last 2 years. HVAC controls are working normally. The car is garaged, so it is above 50 degrees F in the morning. It was less than 50 degrees outside when started in the PM. Any ideas what could be causing this noise?
Thanks in advance! Brian

Three things ,
one is the defroster pod diaphragm has a leak , switch to floor operation at the HVAC head it should stop
or the blue check valve is whining under the hood at the booster, open hood feel the valve, if you feel vibration then the valve should be replaced.
Last is the setting motor squeal,
l move the temp selector colder or warmer with the key in the run position engine off

Mr. Merlin you are so so good! The whining noise occurs on startup and when sliding between temperatures cold or hot. PM Sent.

Great tips, as I have to check that too. It sometimes sounds like Curly from the Three Stooges is under there..."Woop woop woop woop woop!"

My '88 has a whine from the passenger seat area.

It only seems to happen when travelling with my wife, and at speeds that the police would call "excessive".
If I decelerate, the whining stops.

Any suggestions?

Duct tape? :icon501: