I have been reading on AC upgrade and still don't understand what upgrade is needed? I just bought a 2000 s430 and the ac blows fine it's just not blowing powerful enough especially on the side vends of the driver and passenger as well as the rear vents for the rear passenger. Any idea on why this is happening. I have a EC button, but some people says that the dealer has upgraded them to AC off control. All the help would be appreciated as I am going to talk to the dealership again.