If your vehicle is overheating but not blowing warm air from the heater, the problem is more than likely your thermostat.

If the thermostat gets stuck closed, it won't allow fluid to flow and ends up overheating the coolant already in the engine. If your vehicle is not getting up to temperature when driving, the thermostat is more than likely stuck open and your engine will not get up to the proper operating temperature where it runs the most efficiently. To fix this problem and get your vehicle's heat restored, replace your thermostat.

This part was designed to fit like a stock unit, allowing your engine to reach operating temperature properly and cool efficiently.