1 side is hot 1 side is cold , heater what can the problem be an where do I lo

you have a a/c heater blend door issue.seek a diag the cost should be approx 400.00 parts and labor.

The side that is blowing cold, has a bad blend door motor.Its the motor that moves the door in between the heater core and the evaporator to ajust the temperature on passenger or driver side of the vehicle.The blend door should not cost more than 135 dollars and its a pretty simple job , you can save yourself around 400 dollars on labor if you do it yourself.If you need more info just email me at watsonautoservice@gmail.com , my name is Rick Watson