the rear heater is only blowing cold air. front heater works fine. on 2005 Kia Sedona

The heater in the back of the van stopped blowing hot air. This just recently happened in the last mth. Last winter it worked fine. My heater in the front of the van works just fine. My kids are freezing. Please help. What would cause this and would it cost alot to fix?

Asked by for the 2005 Kia Sedona
I would have to see the van first hand and look to see if the heater controls are working correctly or more unlikely to see if air could be trapped in the rear heater. Kia as a car manufacturer put a lot of great technical information and work shop manuals on line for free for Kia owners.