It's pretty easy actually, I just replaced it on 02 c320 wagon. Going from memory, you'll need to unbolt the driver's side engine mount (13mm) from the subframe of the car. The compressor is held in place with 3 very long E torx (E10) screws that can be accessed from the top or bottom. The hoses are disconnected from the top (Allen bolt with wiggle joint). It helps to remove the engine cover and coil packs on the driver's side. You will need to jack up the engine on the driver side by about 1 inch in order to unbolt the rear compressor bolt. You'll also need to unplug the ac control plug after removing the hoses. Also remove the belt tensioner ( 2 Etorx bolts) Once all that is done, the compressor is easily removed from the top between the engine and the radiator. Installation is in reverse. Check the oil in the old compressor. If it's black with metal flakes you'll need to flush the system and replace the expansion valve and condenser. If you're replacing the compressor this is the time to also replace the driver's side engine mount since you have easy access now.

Cheers

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CENSORED due to not family friendly words