Annoying Whiney Noise When Rear Defrost Is On - BMW Forum

LeeTone · 11-04-2004, 12:06 PM

Ok i know someone out there must have a similar problem....I have a 1992 325 i and whenever i put the rear defrost button on, i get a real annoying high-pitched whiney sound (it's not too loud but goes up and down) that seems to match the engines rpm's as i accelerate/decellerate...the sound itself seems to come from the rear glass area...any help is much apprecciated.

used

wulley1 · 11-04-2004, 03:39 PM

does it do it when the radio is off?

LeeTone · 11-04-2004, 10:23 PM

It ONLY MAKES THAT NOISE WHEN THE RADIO IS ON...

xsperf · 11-04-2004, 10:38 PM

ahahaha lol, thats why. that sound is actually ur speakers, its because the engine does something funny to the frequency, or something of the sort, not exactly sure what it is, try playing with the antenna, wherever that is

thekid · 11-04-2004, 10:55 PM

If I am not mistaken our antennas are actually on the rear glass, as is the defroster. So when you turn the defroster on, for some reason, that is interferring with your antenna signal... Not sure what could have happened though... Also I am not sure how to move or replace your antenna or the defroster... Sorry I couldn't help more, but I would guess that some where the deforster is touching the antenna.

LeeTone · 11-04-2004, 11:02 PM

Ok that would make sense, i'll play around with it and see...

wulley1 · 11-05-2004, 07:48 AM

do you have an aftermarket radio or is it stock?

BLACKBMW · 11-05-2004, 08:47 AM

Firstly, it is called "suppression" and its normally associated with older cars that have newer stereo systems in...

The de-froster is interfering with the stereo by emitting a signal which your shitty wiring is picking up (no offence)...this is then transferred into that high pitch whining you hear and the output is coming through the speakers in your rear parcel shelf...

There are solutions ranging from very expensive to free

Very expensive - re-wire the car stereo completely or fit an anti suppression unit to your stereo

Free - dont use the defroster

J...

LeeTone · 11-05-2004, 11:19 AM

Yes it has an aftermarket MD stereo in it (bought it like that)...how much for one of those suppression units and can you get them at any car audio type store?