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Old 05-04-2003, 04:17 PM
Posts: n/a
Thumbs up typical hi-temp, manual fan switch override implemented. whoo-ho!

I’ve read SO many posts complaining about the hi-temp condition associated with MB fan control. I feel your pain and share your sentiment, and decided to do something about my malady.

I just added a “manual override/control” circuit on one of my bikes and hope to do same on my W202.

We’ve all heard the complaint many times: the auto fan circuit is typically too late to engage for many’s taste. Sitting in traffic , eyes glued to the raising gage , wishing the fan was on NOW , anxiously awaiting the breeze

I’ve seen the excellent work posted here (cant remember who to credit) on the lowering of the fan circuit temp through changing the resistor, but knew that what I wanted was MANUAL control (actually override) of the fan.

What I now have is this: an unmolested auto fan circuit, and a manual FAN ON override controlled by a switch.
Switch off = 100% stock auto temp fan. Switch on = fan ON now.
The beauty is in the simplicity. Approx $10 purchased a 2-position auto grade illuminated switch, roll of 16ga wire and an assortment of connectors. If anyone wants further details, just post request here and I can explain the circuit.

This bike (water cooled) seems to be quite susceptible to rapid heat buildup during low speed operation in high ambient temps. Stop and go traffic pushes the temp up quickly, and just as in the car, I was stuck wishing that the fan was on NOW and that the gage was declining, or at the very least stabilizing. The fan would always engage much later (higher temp) than my comfort level, and repeat at each painful long stop light.

NEXT STEPS- get the info to design a similar circuit for the W202, it cant be that hard! I want to keep the MB circuit intact (or at least easy to return to) and add a manual override switch to be used when desired.

I do not have a W202 wiring diagram, so if anyone does have it, I would REALLY appreciate a copy or description of the fan circuit in any manner you can provide it.

i hope this sparks some thoughts, - benton (now smiling)
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