My heat only works on driver side. passenger side, defrost, and back heat doesnt work.

Most likely an inoperative mode door. Mode doors open/close to change the direction of air flow between your vents, actuators are what control them. To fix you have to determine which one is not working, then decide how to get to it - some can be reached through the glove box opening, or by pulling the dash air bag, or worst case scenario by loosening or removing the dash.

There is a mode door in the center console and 3 under the drivers side under the dash by the radio heater. One passenger side far right by the air filter. Your console one isn't working and one under the drivers dash. After you replace them the free repair manual at autozone .com will tell you how to sync them. I can't remember it's hold power button and recirculation button for 5 seconds with the key in the on position and it will reset them