The heating system is the "H" in the HVAC system.  This system is made up the Heater Core, Blower Motor along with many hoses, relays, switches and sensors.  If any of these item's malfunctions, your vehicle will not produce heat.  Even though heat may not be necessary for yourself or your passengers, it may be necessary for your vehicle's cooling system to work properly.  You may not know that your heat is not working properly if you are not using it, but the vehicle will let you know by the gauges or how it is driving.  If you have any issues, please give us a call so we can make sure your vehicle is not at risk of overheating.