Tagged: Resistor

March 28, 2021

M117 fan controller prototype

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...

Mercedes

December 2, 2020

M117 Auxiliary fan cut-in modification

Under normal operation, the auxiliary fan on the M117 engine cuts in at 105C. It can also be triggered by A/C system pressure. These settings work fine to keep the engine at the correct temperature. The challenge is that most of these cars have been converted to R134A refrigerant. R134A is far less efficient than R12. The A/C system in the W126 was designed...