the test cable for the blower motor is behind the brake booster, to get to it you will need to peel the weatherstripping from the windshield and also unscrew the drain tray.

The aux fan low speed is wired through the ceramic resistor. It also has a tendency to burn the wires into a crisp. If they are then remove the headlamp to repair it. The fuses for the low and high speeds of the aux fans are in the panel that is behind the engine fuse box.

You will find two relays with fuses, one green and one blue, the green is high speed with the 30A fuse and the blue is low speed - originally it had a 15A fuse but was later updated to a 20A fuse, check those.

to trigger high speed aux fans at any time, simply unclip the wiring plug for it on the Tstat housing and the fans should run full speed.

If you are missing both speeds, test for voltage at the fan connector near the driver side headlamp, if you are missing voltage there then carefully check the resistor again. The high speed is also tightened on the output leg of the resistor. When the wiring burns there, you may sometimes lose high speed too.

btw - this car is of the crumbling wiring period of MB, make sure the wiring is clean.

for starters, clean the cabin temperature sensor in the interior next to the dome light. (blast from duster can). If you are stalled and scratching your head then pull the error codes from pin 7 of the diagnosis connector in the engine room.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)