on my van the back air comes out hot in the front cold why would that be?

You need a blend door actuator. To replace is easy. Pull the radio to get to the top bolt and then pull the bottom cubbie by taking out 4 screws 2 on the left 2 on the right. Back them out half way then use a flat way and pop them out. To access the bottom 2 bolts and wire clip. Then do everything thing back in reverse.