10million ohms is too much.

The fan should run on low with the red switch bridged. It only closes above 250psi. If the compressor is on and the high side pressure is below 250, the fan may not run.

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Benzmac:
Donnie Drummonds
1991 GMC Syclone
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM