Since it got colder out, I've notice a funny sound or two coming from somewhere in the depths of the dash. When I have the ACC set to around 22C (basically, a mixture of heat and cool) I hear a "weeeeeeeeeee-ohh-weeeeeeeeeee-ohh" sound. If I turn the dial to cool, the sound goes away, if I turn it hot, there is more "ohh" than "weeeeeeeeee."

I don't know much about how this system works, but I'm assuming it might be some sort of switching solenoid that regulates how much heat is coming out or something?

Also, after being on for awhile, the blower starts to sound like a cricket, unless I turn the fan on high. Sounds like it's coming from under the passenger dash. Where is the fan located, how hard it is to get to it, and when I do, can I just "oil it up" or put some graphite on the bearings or something?

Any help would be appreciated. I'm thinking about doing a road trip soon, and I think I would go nuts if I had to listen to this the whole way or keep the radio going the whole time. Sometimes, I just like to listen to it go down the road. Minus the "weeeeeeeeeee-ohh."

Thanks

__________________
B
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1983 300SD

Look in your mirror for red lights

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1977 300D Lost coolant while someone else was driving
1983 300D Can't run without oil
1985 300SD (gone but not forgotten)
1990 300TE 4matic Sold
1991 Yamaha Venture
1975 Kawsaki 250 triple
1974 Honda 200CL
1951 8N Ford
2008 Wildfire 650C

I'm going to make a WAG and say that the sampler motor is acting up. I say this because the SDL did the same thing. Kind of a high pitched scream that is intermittent. Would typically go away once the sampler motor warmed up.

All you need to do is to pull the motor out, clean it thoroughly, put a couple of drops of oil on the bushings and put it back together. It's located right above the passenger kick panel.

You may also have some issues with the blower itself. If the sound varies with the blower speed, it also could use a cleaning and a couple of drops of oil.

His 1983 300SD doesn't have a sampler motor. Later models did.

A venturi off the fan box draws the air past the temp probe in the type I chassis 126.

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

Hi,

I had a 300TD 1979 that would make a wheeeoooohh sound that sounded kind of like a vacuum leak. It made a faint squeal somewhere behind the climate controls.

Well, one night, while testing the car after doing some major engine work, the squeal got louder and louder and louder and suddenly smoke came out of the center vents. I BS you not! I had to pull over.

Originally I thought I'd blown the AC coil or the heater coil but after I took the components apart it was apparently an electrical fire. The wire and switch to the AC on/off rocker switch was melted.

I'm not sure to this day what exactly happened. I don't think it was a vacuum leak. The sound would fade away after I killed the engine so I thought it was a leak...but I don't know how the sound and its increasing volume managed to fry my wiring and blow the fuse to the fan. I sold the car shortly afterwards.

Anyway, I suggest you take this very seriously before you have a disaster.

Cheers,
Yoko

Thanks. I was not aware of this.

I went digging through my car a little just to see what there is too it. I checked this sound out when the car is off. The sound appears to be coming form the attached picture. Seems to be where the hoses for the heater core go. Please let me know if more explanation of the picture is needed. Also, this flap here doesn't seem to function, although the passenger flap does. Would this possibly be making the sound? What makes this open and close?

One more thing, just to clarify, the chirping and the wee-oh are not related, and the wee-oh is not too loud or screetching, more like an electrical/motor hum/issue. Hard to explain, sorry.

Thanks,

Attached Thumbnails

   

__________________
B
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1983 300SD

Air sampler motor?
My air sampler motor makes that noise when ambient drops below 30F.
It is located behind glove box to the right.
Remove it, take it into a warm room for a couple hours, then open the case gently, lubricate the bushings with sewing machine oil, reposition the motor in housing, quickly take it to the car and test it, be prepared to reposition motor in housing a few times to get it perfect.

__________________
ASE Master Mechanic
asemastermechanic@juno.com

Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
Vehicle build.
Fleet Durability
Technical Quality Auditor.
Automotive Technical Writer

1985 300SD
1983 300D
1984 190D
2003 Volvo V70
2002 Honda Civic

https://www.boldegoist.com/

OK, now.

Who's telling the truth here?

Does the W126 ('81-'85) have an air sampler motor, similar to the '86-'87 or doesn't it??

What you describe, fits a blower squirrel cage touching plastic.
The 1985 300Sd does have the air sampler motor.
I confuse the early W126 climate control with late on occasion, blame my mental pause.
Have a great day.

Well, the wee-oh has seemed to fix itself for now. But the criping is back after lubing up the motor. I guess I pull the brushes and replace those next.

Thanks everyone,

__________________
B
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1983 300SD