I have a 1999 SLK230 Kompressor with 90K miles. I am getting a very annoying high pitched 1000 HZ noise coming from under the glove box. It happens only when the engine is running and the fan switch is turned off. It comes and goes but will stop if I turn the fan switch on to any speed. I removed the kick panel under the glove box and took off all the cables to the fan and other connectors I found and even removed the air filters. The noise would not stop. It may even be coming from above the fan but it is hard to determine lying upside down with a flashlight.

Any idea what else is under there or what can be causing the noise?

This reply is in no way helpful for which I apologize, but I am curious as to how you have determined that the noise is 1Khz. 1Khz isn't very high pitched, in audio it's considered mid-range.

Does the pitch stay constant? Does it vary at all? Does it sound like a mechanical noise or could it be coming from some sort of buzzer?


Just curious. That is a strange problem. Do you have crickets in your neck of the woods?

Suspect would be aspirator fan .
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A Dalton

I have a 1000HZ tone generator I used to align my old tape player record head. Although I did not measure it or bring it to the car, it sounds very similar. The tone does not change frequency or volume and stays a smooth "eeeeee" tone once it begins. It comes and goes but it has been getting longer as the days pass since it started a few weeks ago.

I even pulled the air filters assuming they were clogged but no change even with them out and the fan connector disconnected.

It does not sound mechanical but rather electrical - no spinning up to speed or whirring fan sounds. I have heard similar sounds from failing capacitors and vacuum tubes in old stereo equipment.

BTW it only happens when the fan is off set to 0 and the engine is running. If I turn off the car the sound stops regardless of the ignition key position.