High pitched whine when ignition on in 124 - PeachParts Mercedes-Benz Forum

muleears · #1 02-09-2007, 09:01 AM

Recently I hear a high pitched whine whenever the ignition is on. I thought at first it was the blower motor but I still hear it with the ventilation off. Does this car have a "sampling fan" on the right side of the dash somewhere? If so how can I replace/disable it? It is very annoying. Searched the archives but all I found was blower motor stuff. TIA

clint77002 · #2 02-09-2007, 09:53 AM

While replacing the dash in my 87 300D (original one was cracked badly and I found one in prefect shape), I found a small blower at the far right side. You should be able to get to it by reaching up under the dash. Its about half the length of a banana and about as big around. It is held on by little aluminum ears that protrude from the dash panel itself. Mine was disconnected (wires cut) so I have no idea what its used for. If you want to replace it, I have my original one that you can have for shipping charges. I don't know if it works or not but I can test it tonight.

Clint

lrg · #3 02-09-2007, 11:28 AM

The sampling motor pulls air in from the small intake next to the light over the mirror (the 123 has the intake on the top center of the dash). The interior air is drawn over a temperature sensor just behind the ceiling intake and is drawn down a tube through the right hand A pillar to the sampling motor. The temp. sensor provides input to the climate control unit which adjusts the interior heat/cooling. Having this work it important if you want the climate control to work. My sampling motor started making some noise and I just removed it and lubricated the bearings with plain motor oil and it's been fine now for about 2 years. You'll also sometimes see a motor come up for sale on EBay if yours has to be replaced.

muleears · #4 02-09-2007, 11:45 AM

it attached under the dash, screws, bolts "C" springs? What will I need to get it out?

lrg · #5 02-09-2007, 01:44 PM

It was a couple of years ago so I don't recall the details but as I remember it wasn't a big deal to get it out. Like most under dash jobs, it helps if your elbows are double jointed.

clint77002 · #6 02-09-2007, 02:05 PM

Its held to the dash with aluminum "ears". The aluminum is the base for the dash. Just lift them up (2 of them) and it will lift out.

speedy300Dturbo · #7 02-10-2007, 02:14 AM

Quote:

Originally Posted by lrg

It was a couple of years ago so I don't recall the details but as I remember it wasn't a big deal to get it out. Like most under dash jobs, it helps if your elbows are double jointed.

It's a lot easier to get to it through the glovebox. Remove all the two-piece rivet clips holding the glovebox liner in, pull out the light and the latch eye (two upside-down phillips screws) and pull the liner out. The sampler motor is to the right, almost directly underneath the air nozzle.

muleears · #8 02-11-2007, 04:54 AM

Pulled it out, put a drop of oil on the shaft behind the fan. Now all I listen to is blissful silence

Thanks to all of you for the help.