Your vehicle is designed with two blend air doors that allow separate temps to different areas of the vehicle. Since you have heat on one side, that tells me there is no problem with the heater core or the engine thermostat. That leaves one problem, a blend air door. If the door isn't functioning to allow heat to enter the vehicle (it's stuck or damaged), you won't get heat to the one side of the vehicle. That was easy to diagnose; however, the repair is different. The dash will need partially removed to access the heater box and the blend air doors. It is a cumbrous job to complete. If you chose to do it yourself, I recommend that you purchase a good repair manual that has pics and step by step instructions for you to follow. For me to try and provide that many steps via the internet allows too much room for error.
Let me know if you have other questions.
Friday, January 30th, 2015 AT 8:40 AM