The heater control valve is located on the car dashboard. It is a small nob, usually a circular control that can be turned to the left. When turned, this nob operates and controls the heating system. It opens a vent and turns on a fan that directs heat into the car cabin. Heat control valves also switch on the car's interior heating system, which is made up of a series of vents that open and close, channeling hot air from the engine into the car.
The heating system in a car is all tied to the radiator. The radiator is what disperses heat from the engine. As soon as the car is turned on, the engine begins to generate heat from the friction of components. This heat needs to be dispersed away from the engine to protect the sensitive parts from damage. This is done by flushing coolant through the engine itself. The coolant absorbs the heat and carries it from the engine to the radiator, where it is released into the air. A heater control valve operates the system that redirects some of this heat into the car.
A heater control valve is used to control how much heat is diverted into a car. This is done through vents that lead from the radiator to the car firewall. When the heater control valve is turned on, heat is not only let into the car but blown inside by the fan. Turning the heater control on to high, blows more hot air into the cabin. Without the fan blowing the hot air into the car, the heat would linger near the firewall. When it is blown into the car, it is forced inside by air currents created from the fan. That allows heat dispersion to occur and therefore the entire car is heated to comfortable temperature. Without this aspect, the area near the firewall would become very hot, and heat would circulate more slowly throughout the cabin.
