air conditioner quit blowing cold air. on 1999 Mercury Grand Marquis

how do I recharge it

Asked by for the 1999 Mercury Grand Marquis
if it quit suddenly, it may have blown a hose, seal or compressor gone out. need to know if it has freon in system before trying to charge. if it does, no way to know how much without being evacuated. need to take to a shop, have them inspect a/c system.