I have a 2001 Dodge Ram 3.9 that leaks water from the condensate drain tube when I run my heater. Is this normal?

It usually happens when you run the A/C, unless you have condensate that has backed-up beneath the evaporator coil. Take a long wire and run it up through the drain tube. Be ready for possibly a quart of water to gush out.

If the A/C runs while the heater is on to dehumidify the air you might not have a problem at all. Still, I would run the wire up to make sure there's no blockage.

Is the water clear? Or is a mixture with coolant?
Any odors from inside the vehicle?