Now we have hit summer here in Sydney, it was apparent that the auxiliary fan was not working. The fan is triggered either by high coolant temperature, or refrigerant pressure. High coolant temperature causes the fan to run at full speed. Refrigerant temperature can trigger a slower fan speed based on a resistor. Before I just jumped into W126 auxiliary fan replacement, I tested the existing fan.
The first test is to jump the wires at the coolant temperature probe. This should trigger high speed running. The next is the sensor on the A/C receiver/drier which should trigger low speed […]
