A couple of months ago I tried a modification on my 560SEL to trigger the auxiliary cooling fan earlier. The primary reason for this was to provide adequate air flow over the A/C condenser in stop/go traffic. The W126 A/C was designed for R12 refrigerant and is marginal at best with R134A. I used a resistor to trick the fan into running at a lower temperature. It worked, but the temperature kick in was a bit higher than I wanted and the wiring was messy. I thought a better solution would be to build a proper M117 fan controller.
The […]
