what keeps your car cool
 

I just ordered one of Jim F.'s "cool Harness." I have read a lot about them here on Mercedes Shop and they look like they work well. Has anyone had any negetive experiences with them (i.e. fuel injection redings, etc.?)

thanks!

I made one myself and it works great, now anyway. I suspected something was amiss with my car so I ended up with an odd problem. The applicable failure mode was the hysterisis, the fans came on at the right temperature but went off at a lower than expected temperature. The lower temperature was below the thermostat so once the fans came on they wouldn't go off unless the engine got real cool and the thermostat closed, but then it stopped water from going to the radiator which is where the fans were. I just increased the resistance to raise the lower temperature above the upper temperature of the thermostat.

Now if I can just figure out how to bypass the ignition switch to keep things from roasting after I shut the engine off.

cool
 

what exactly did you buy?

The cool harness seems to be a sensor or a switch that senses engine temps and will kick the fans in at a lower temperature than the regular Mercedes temp which I believe is around 102 degrees. I have provided a website: http://pages.prodigy.net/jforgione/MB_S500.html

cool harness
 

diagram for cool harness


it is an resistor that turns the fan on sooner, rather than a sensor that senses engine temp

I just soldered in a resistor. cost me nothing. works wonders.

Resistor
 

sounds good to me, what value was the resistor you used?

1.1k ohms