why does water come inside my truck whwn ac is running on my dodge 1500

The drain for your Evaporator case is probably plugged. The AC Evaporator is a black plastic case on the passenger's side of the vehicle that holds the heater and AC components. You may have to get under the truck to find it but there's a black plastic nipple that allows clear water to drain from the evaporator that is probably plugged by some leaves o other debris. If you can find it, gently clear it with some wire or compressed air.