Heat

Make sure the coolant level is full. Check to make sure both heater core hoses are hot when the heat is on and the engine running and hot. If both are hot, then check the blend door. If only one is hot, flush the heater core. NOTE: I can't tell for sure by your post if this is a temp issue (which I think it is) or an air flow issue. If it deals with air flow direction, check for vacuum leaks under the dash and where the vacuum supply comes from under the hood.