Okay, that leaves only a couple issues that can cause this. First, I need you to start the engine and allow it to warm up to normal operating temp. (You can do this after a trip too). With the heater on high, I need you to feel both heater core hoses. Both should be very hot to the touch. If only one is hot and the other warm, chances are the heater core is partially plugged. If both are hot, then I suspect the blend air door is not opening properly and allowing the heat to enter the vehicle.
Check that and let me know what you find.
Thursday, January 2nd, 2014 AT 2:46 PM