I'm not getting cold air with the AC. The disc associated with the AC pully on the poly belt, the lower right one looking from the front of the engine, is always turning with the engine running, whether the AC is turned on or not. I am used to vehicles where that only turns when the AC is on. Does anyone know if it always turns on an 07 ML350?

I tried to add coolant to the lower pressure side filling attachment. But the Mercedes receptacle is so deep I am not sure the filling attachment I have is reaching down far enough to open up the valve to allow coolant into the car's AC system. Does anyone know if a special attachment is necessary for filling a Mercedes AC system?

The coolant level must be really low because when I use a small screwdriver to depress the low pressure valve inlet only a tiny bit comes out, like a tire with 3 psi in it. With the engine running, when I turn the AC on with my friend's head under the hood right over the engine compartment there is no audible change in noise, no clicks, no nothing.

Anyone know what I can do to get my AC going?