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Q: fan runs at high speed when car it turned on.

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upon turning the automobile on, the Fan comes on at a high speed and never goes off until the car is turned off. Also the temperature gages in auto is incorrect.

My car has 300000 miles.
My car has an automatic transmission.

A: Hello there, you have a few different fault...

Hello there, you have a few different faults with your 2000 Mercedes. Your car's fans have two speeds, low and high. The High speed setting should only be on during heavy load and high temperatures. The fans should shut off when driving and speed. The most common faults are the coolant temperature sensor, fan relay, failing fans, or a wiring harness fault. A qualified Technician such as one from YourMechanic will be able to diagnose your fan issues and make any repairs required.

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