Quote:
Originally Posted by Jeremy5848
The Hall sensor is in the instrument cluster, near the speedometer cable. It is a plastic piece with a green wire. You will see that the green wire goes to a distribution block forward of the instrument cluster. One or more green wires come off of that block and there are unused terminals. In the W124 cars, the Hall-effect speed sensor is used by the outside temperature display (stops updating when the car is stopped) and in the climate control (slows the blower a little when the car is moving at highway speeds to compensate for the "ram air" effect). It should not be difficult (he said) to find a way to use this signal. I would recommend having the climate control switch to 100% recirculated air when the car is stopped.
In the meantime, just push the "recirculate" switch when you stop the car. That starts a timer and puts the system in 100% recirculated for 30 minutes.
A friend has a similar problem and finds that biodiesel is less harmful to her than petroleum diesel.
Jeremy
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Greetings,
Next time I pull the dash I'll take a look at it. Some of my early grad work involved measuring the Hall effect so it has a charm for me.
I think the recirc switch only puts the car in 80% recirc and it only enters 100% recirc when the CCU is shutoff.
The recirc button performs differently then other MBs I've had. On all others when I engage the recirc there is a noticeable increase in blower speed. That does not occur in this car. Instead I hear a quiet relay engage underneath the back seat and the 6-port vacuum realy behind the glove-box opens the port to the recirc pod but no change in blower speed.
I currently run at continuous 80% recirc by having the source vac line tee into the recirc pod (80%). I then altered the action of the recirc switch such-that engage it will close the recirc from 80% to 100%.
I've now decided that I would like to a 3-way choice: 0%, 80% or 100% and have the option of manual and/or automatic operation.
Interesting what you said about your friend being less perturbed by bio-diesel. 10 to 12 years ago the affliction crippled me and I could not work for almost 3 years. It was a challenging process to recover. Next time I'm over by Berserkley or up in your area I'll get a tank of bio-diesel and see if the exhaust affects me differently.