my heat wont stop blowing in car even though its off

Most likely you have an electrical short, when the heater core was replaced, the electrical wire of the blower motor got sliced and is touching the metal of the body and is turning your blower on continuously, hence the problem you have. This problem did not exist before and the only way to turn it off is to remove the dashboard again and check the wiring. I know it is a pain, but there is no way around it.

My 1998 bravada has heat blowing out of the vents....even thought it is turned off.....how do I stop this