Any one can help me out on this. Thousand thanks to all. I have 2003 mercedes sl500 fan is not turn on when hot also the ac clutch engage automatic when engine start. Please help...

 

both issues are actually common on the 2003 Mercedes-Benz SL500 and may be related.

When the cooling fan doesn’t come on when the engine gets hot, the usual suspects are the electric fan itself, the fan control module, temperature sensor, or wiring. This car uses an electric radiator fan that should kick in based on coolant temperature or A/C demand. If it never turns on, first check the fuse and relay, then confirm whether the fan motor works by applying direct power.

 

Be aware that wiring damage will cause the fuse to blow. If the fuse keeps blowing you will need to inspect the wiring to see if there is chaffing and shorts to ground. That was a problem in the ML series - the wiring passed over a sharp edge that wore away the insulation causing shorts.