Q: Car is overheating 2005 Hyundai Accent

Hello - both the overheating and the lack of heat out of the heater could be caused by inadequate bleeding of the cooling system when you put coolant in the car. To get all the air out of the system - with the radiator cap slightly loose - run the engine (fast idle) with the heater in the Max Heat position, fan on Max, until the engine has come up to operating temperature on the gauge, and air bubbles have stopped coming out of the radiator cap. If you still have overheating problems after properly bleeding the system, I would recommend an inspection of the cooling system by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.