guys,
i have had this problem for a while now. today i was marking up for the plan of laying down real carbon fiber over the faux interior it became worse. it used to be that when i shut off the AC, the noise comes. this time it's not as loud but it lingers even with the AC on. the noise is there occasionally and sometimes it goes away for a few minutes before it comes back.
anyone got any idea what the problem might be?
much thanks, everyone. this forum and all of u wonderful contributors had been a great help since my purchase of the car.

 

Can you describe the noise? Is it like a fan that the bearings are shot, high pitched then the pitched gets lower as the fan is slowed down? Is it a squeal, rattle?

 

thanks wizard, for showing up.
well, i would describe it as a squeal. u know, the type that extremely high pitch that's unbearable to ear.
when i turn the AC faster or slower, the pitch is usually unchanged. even if it does, the variation in tonal change is not too obvious. when i shut off the fan completely, it's quiet for a split second and then the same pitch returned with a much high volume. this is when it's unbearable. turning on the fan again, i would get a moment of quiet before it reaches it it's normal squeal. within minutes, it goes away. then awhile later it came back.
all these happened while i was sitting in the car trying to mark up the dashboard. it gets really hot this time of year in MA so i had the car started for AC. though engine is running i was stationary.
and yes, i tried turning off the car and start it again. it yielded no results.

 

I live in Chicopee, so I know how hot it is the last week or so. It's got to be in the fan housing as the noise is inside the car. Could be something is in the fan housing hitting the fan as it runs? But you said the squeal is there with the fan off? When you say you shut the fan off completely, are you turning the AC off? I think the HVAC blows some air even when off, for circulation. Have you changed your cabin filter recently? Might be clogged and no air is getting thru? Does it make the noise when the recirculate button is on? I don't think the fan stop when the system is off. I not sure, but I think the fan is always on to circulate air on the car?

 

if the sound does not change with different HVAC blower speeds then it is not the blower motor.

the main engine elex cooling fan will operate at an infinite # of speeds depending on temps and refrigerant pressures which could explain the change in the squeal concurrent with you turning the a/c on and off. it could be the belt tensioner or one of the pully bearings, but hopefully not the a/c compressor bearings, that would be expensive.

remove your serpentine belt and run the engine, that will eliminate all but the engine cooling fan.

BTW, the belt routing diagram is in your owners manual in case you forget [IMG][/IMG].

 

Hi trymolam. I have a 1999 C280 too and my car makes the same noise you are describing as soon as I turn off my A/C. The second I turn on my air. It doesn't matter what temperature or how high the air level is. The noise goes away. Only when turned off. Do you know what the problem was exactly with your car? Thanks


QUOTE=trymonlam;16762]guys,
i have had this problem for a while now. today i was marking up for the plan of laying down real carbon fiber over the faux interior it became worse. it used to be that when i shut off the AC, the noise comes. this time it's not as loud but it lingers even with the AC on. the noise is there occasionally and sometimes it goes away for a few minutes before it comes back.
anyone got any idea what the problem might be?
much thanks, everyone. this forum and all of u wonderful contributors had been a great help since my purchase of the car.[/QUOTE]

 

[/QUOTE]

So my 96 c280 is doing the same thing. Only when I turn blower off it makes an unbearable high pitched noise. 2 years ago the dealer replaced my fan motor because it was full of water. The new blower never seemed quite right and for the last 6 months has been doing this. I have not had time ti take till dealer (2.5 hours away) and so for now I just leave fan running so it doesn't squeal