It freely moves back and forth as if its not gripping. I've had to adjust the temp by going in front of the lower passenger seat and adjusting it manually where the cable is. How do I replace the lever?

 

Remove your right rear speaker. Hold it your left ear upside while hopping counter clockwise and humming the sesame street theme. Then down a cold 2 liter of Dr Pepper while chewing on pop rocks. Line up 14 small sea shells in your driveway and meditate. Reinstall speaker. Repeat as necessary until your heater works.

J/P Looks like you'll have to pull the assembly out of your dash and see whats broken. Could be the lever or maybe even the cable.