Why is my passenger side floor getting wet from using my A/C?

This is not rain or puddle related. There is not smell or warmth that I would expect to find from a heater related leak. And is I suffer not using the A/C for a couple of days after towel drying, it drys up.My local shade tree mechanic seems stumped after thinking he fixed it after blowing out some tube??? Help on this would sure be appreciated.
Thanks!