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Old 09-04-2002, 07:03 PM
ke6dcj ke6dcj is offline
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Join Date: Apr 1999
Posts: 2,632
Question Modifying a MB dual coolant sensor to trigger an electric fan?

I was wondering if the electrical wizards here can help me.
I want to replace the SINGLE coolant sensor with a MB *double* sensor,
that way I don't have to use the sensor that sticks into the radiator
fins to trigger my electric puller fan that replaces my viscous fan.

Pins 1 & 4 act just like the "blue" coolant sensor that triggers the
Aux.
fans.

However, Pins 2 & 3 have a smaller value.
The Derale adjustable thermostat uses a sensor that gives higher values.

Here's a brief table (yes I know, it's incomplete) in OHMS:

Double-sensor
Celsius Pins 1/4 Derale
44.4 970 5525
48.9 810
54.4 730
60.0 570
65.6 470
71.1 396
74.4 361
76.7 345
82.2 309 2924
85.6 268
87.8 252
91.1 228
93.3 215
95.6 195
97.8 190 2750
98.9 188 2460
100.0 186 2240


If I want to trigger the Derale to come on at 93.3-Celsius how can I get
the MB sensor on pins 1/4 to mimick the values of the Derale (note- it's
adjustable to a point)?

I was thinking of adding in series a resistor (I think resistors in
series you add them together) that would get me in the "magic range" but
the resistor value cannot be high-enough to trigger it on until
93.3-Celsius.


Thanks in advance,
:-) neil
1988 360TE AMG
1993 500E
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