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Stan, Mercedes Technician
Category: Mercedes
Satisfied Customers: 3526
Experience:  Technical support engineer
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My 2001 Mercedes S320 has developed a fault with the heating

Customer Question

My 2001 Mercedes S320 has developed a fault with the heating / air conditioning. The fan will not operate even though a new fan has been fitted. The aircon system has been re gassed and the E C light is out. My local Merc specialist says that the fan is ok but there is no communication between the instrument cluster and the fan.
The car was recently off the road for 6 months over the winter. All the lights on the instrument panel work and the fan speed indicator goes up and down as it should.
Submitted: 3 years ago.
Category: Mercedes
Expert:  Stan replied 3 years ago.

Stan :

The fan has a speed regulator relay installed in the ventilation box. It receives the speed comand from the AC control unit and then adjusts the current to the fan. Please have it's voltage supply checked. Usually this regulator fails.

Stan :


JACUSTOMER-j5mk8c5y- :

It will be next week before I can take it to the garage to try it. I'll let you know!

Stan :

No problem, please reply whenever it is most convenient for you.