passenger side cooling/driver side so-so

haven't ran the a/c in my car for a few weeks and then turned it on last week to feel nothing but hot air. put a can of freon/oil/sealer in and then topped off with just freon. now the passenger side cools like no other while the driver's side is just barely cool. any ideas? where to look? how to get into where ever i need to look?

also, have noticed puddles of water only after heavy rains in the passenger floorboard. could this be affecting anything with the vents?

99 gt, dual climate zone, 56k miles. no major work done.

thanks.