The fan switch in the drier should be red in color and the pressure switch in the drier should be the updated version with high pressure cut-out. It would be nice to have a new expansion valve for 134a but not a have to. A new drier would be needed as well as having the lines flushed. Be sure to blow out the fins of the condensor and radiator to clean out the road bebris and get max airflow for cooling.
Hope this helps,
14 year MB tech
7 year shop foreman @ independent MB/Volvo shop