I drive a 96 country and I've been having some weird heater problems. When I start it up I have good heat but after I drive for about 30mins or so and I lose all air through the vents no matter what setting its on. I also noticed that in the floor board of the passenger side something is frosting up. But after I turn it off and wait a little while a whole bunch of water runs out of where the a/c drains when its on. My dad suggested that it could be the heater core slowly going out, or maybe something like mud is clogging something, or that my a/c os causing something to freeze. If you have any ideas please feel free to share them.