W201 Squealing Interior Sound in Cold Weather
 

Greetings!

Scipio (1993 190E) is expressing his annoyance at the unseasonable weather...

Now that the temperature has been consistently below zero, a few seconds after I start Scipio up the is a loud squealing sound (like a fan with a bad bearing) for a good several minutes, at which point the sound disappears. It seems to be coming from behind the passenger-side of the dash.

I don't like anything that sounds like a squealing bearing, but I've no idea what's lurking behind the dash and where to begin looking. Any tips would be greatly appreciated.

Kind regards,
Brian

It's the "air aspirator motor" which is a small electric motor by Bosch mounted behind the area of the glovebox. It's part of the climate control system. It sends a stream of air via a tube up the passenger side A-pillar and the tube then goes to the center of the ceiling/visor area where the cabin temperature sensor is located behind the slotted squrare grill that looks like a microphone piece.

My god that was quick!

Thank you, for I now know what it is. Should I worry about it, given that we average perhaps a week's worth of below zero days in a year?

Brian, how loud is the noise? The fan that power the aspirator is a very small electrical fan - smaller than even the fan in a laptop.

If you do a check under "heater blower fan noise" you may find that the heater blower fan makes a loud, squealing sound when the bearings are going. The noise usually is most noticeable at low fan speed and when it is cold.

Try turning on the car with the A/C and heater off and see if the noise is present. If the noise is present with the A/C and heater off then MTI's diagnosis is correct. If there is no noise with the A/C - heater off, then it may be the heater blower fan at fault.

Good luck up in the frozen tundra. :)

Its not that small.....its way bigger than a laptop fan.....Its a bit bigger than a D-size battery overall......

That is the enclosure, the fan itself is not very big. I think I have a spare one lying around. I may take pics and post them.

Where exactly is it located behind the dash??



It just started to squeak when winter started, and its really annoying.




Do I have to pull the dash?

On a later w126 its under the passenger kick panel next to the main blower.....not sure if it'd be similar on a w124....

Another way to test which motor it is . . . the climate control main blower motor tends to "squeak" more under acceleration or braking (the bearings get loaded by the acceleration/deceleration), while the aspirator motor is usually heard on start up or randomly while driving.

Mine sounds like its coming from behind the center vents, or just around them.

The blower motors on the W124 and W201 are located on the engine bay side of the firewall, so you don't have to pull the dash, just the wiper assembly. Being located in the middle makes it a PITA to work on.