2004 C200 Kompressor air-conditioner fault?
 

Does anyone know if there is a known fault with the air-conditioning system in the C200?
My air-conditioner hasn't been working despite numerous changes to the coolant and checks by family friends who are mechanics.
They have told us that there is a known fault in the car, could someone confirm this for me? I don't want to be paying out the ass to have it fixed if it is in fact a warranty job.