My cars ac blows cold but it doesn’t blow hard enough?

If the blower motor is not blowing hard enough i has nothing to do with the AC system.

Replace the cabin filter if it has one.  Check for a dirty blower and bad blower motor or resistor/resistor module.  Check for loose or disconnected ducting.  Clean the evaporator coils.  You might need to see a car AC specialist to get the coils cleaned.

If that's the problem, could be lose air hose, lose vacuum hose, defective vacuum motor, bad controller, etc etc etc.  The cost will depend upon whether it is a Chrysler part # or a Mercedes part #.