What is probably happening is that the drain for condensation has gotten kinked or clogged. On the passenger side the evaporator sits just to the left of the blower motor and it is what gets cold for the A/C to work. There is a drip pan under it that is part of the cover box. On it is a tube that runs through the firewall to let condensation dripp out onto the ground. That is the little puddle of water you commonly see under a car.
So, look for the tube near the bottom of the firewal, passenger side and see if it is kinked or clogged.
You may have to take the blower motor and evaporator cover off to get at the kink or the glog if you can't get it from the outside.