97 TJ Sahara. Here are the problems:

1. I've got coolant leaking from the floor vents on both sides. Replaced the heater core 2 years ago, so it better not be leaking again. Any ideas?

2. Defrost doesn't work. Not sure how the heater operates, but when I turn it to defrost, I hear a bang, like a flap has closed and I hear the pressure of the air trying to flow, but it can't get out. Hard to explain. All other settings (blow straight out, and floor vents) seem to work fine.