wazabii

My 2002 c240 has a very low high pitch whistling noise that comes from under or around the driver dash area. It sounds exactly like your ears are ringing. It fooled me for a while; I thought my own ears were ringing. The sound gets disturbed (goes on and off w/o any pattern) but does not go away when you pump the brake pedals. It comes and goes and I cannot pin point it. The only thing that I can correlate with the sound is that it does not occur if the car is not in motion. I'm thinking it could be some sort of vacuum leak. Anyone have any thoughts? Anyone know what vacuum hoses are around the driver side area if any at all? Any help would be appreciated.

benz-tech

not too much vacuum running under the dash of c240, see if the sound changes with your blower speed. also could be low on refrigerant, try turning off the a/c and see if it changes.

wazabii

I had the "low refrigerant" noise before...got an AC service (2 weeks ago) and it went away but the noise in question is still occurring. It was there before I heard the "low refrigerant" noise and its still there now. The noise is still present with the ac turned off and the blue vent roller knob is fully opened. I'll post what I find out.

BENZITCH

Could be the fan for the temperature sensor.
Sometimes these have a high wind noise to them.
Bruce

wazabii

Where is this fan? Are you refering to the main fan that sits next to the radiator? I'll have to open it up when the fan is on. Thanks for the info.

Srav44

I purchased a used 2001 C240, excellent condition, clean, one owner, 81k miles, Friday night. While driving home I noticed a whistling noise, which sounded as if it was coming from the passenger side dash. It starts at about 25-30 MPH and gets louder the faster I go. No change in the noise regardless of the heat on or off. It stops when the car stops then regains when moving. It's not brakes, motor or anything mechanical but seeks to be air is catching on something and whistling. It's not the hood ornament either. The dealer states they cannot figure it out however, they are a ford dealership and I think they don't want to spend anymore time or money on her.

My daughter is very sick and we spend 1300 a month in copays for her treatments and travel a lot. I cannot buy a car that needs extensive work later or a new car because of our medical cost. I left it at the dealer Saturday (less than 16 hours of buying it I returned it.). I told them until the annoying whistling noise is gone I will not take her. I'm hoping you can help as I really love this car and I feel the ford dealer won't know these types of issues or will not call the local Mercedes dealer to assist him in finding the noise.

wazabii

Sorry haven't been on here in a while...until I bought a new to me c300. My c240 still whistles...even louder now. Mine has been pinpointed as coming from the area of the brake pedal. If I press the brake pedal the noise gets interrupted. Still don't hear it in the winter time but every summer it comes back. Hard to determine as the car needs to be going down the street....seems to come on after you accelerate and then let go of the gas pedal. Wish someone would be willing to stick there head down by the brake pedal while I'm doing 40 down the street...hahaha.