Q&A

 Master

I believe this vehicle has a valve that allows hot engine coolant to flow into the heater core. If this valve is not being operated correctly or is bad, that may cause your problem. I would have the valve operation checked, as well as the diagnostic information that may be stored in the climate control module.
Also, if the engine is not getting up to operating temperature, you may have a bad thermostat casing this issue.
Here is some more info related to this issue: http://repairpal.com/i-have-no-heat-what-could-be-wrong
Good Luck and let us know what you find!