General Information - Interior Heating System

It's nice to have a heating system that works properly in your vehicle. Those drives through frigid winter nights are a lot easier with heat. All it takes is one time when the heater doesn't work to remind us how important this system is.

Note: the following information is of a general nature. Consult a repair manual written specifically for your vehicle to find a description of your exact heater system.

The heater system is most vehicles consists of the heater core; the heater controls; the heater blower assembly, which houses the blower motor and the blower motor resistor; the hoses connecting the heater core to the engine cooling system; and duct work which allows the heated air to circulate in your vehicle (the air-conditioning system also uses this duct work to transport cool air).

Some vehicles may also have a heater core pump and an auxiliary water pump that supplements the operation of the heater system. These components work in conjunction with puller and pusher fans that force air through the radiator.

The system works like this. The water pump circulates coolant through your engine's cooling system and through the heater core. When you activate the heater at the controls, a flap door opens to expose the heater to the passenger compartment. When you activate the fan switch on the heater control panel, this turns on the blower motor which forces air through the heater core. The heated air then flows through the heater ducts into the passenger compartment.

Some vehicles are equipped with an electric heater core pump that circulates coolant into the heater core for fast, direct heating. It is usually mounted on the back of the engine block.

Some vehicles also have equipment to prevent coolant boil-over. An auxiliary water pump is the primary component that helps prevent this from occurring. The auxiliary water pump is located near the puller fan, which in turn is located in front of the radiator. This pump circulates coolant through the radiator after you shut off the engine to prevent the radiator from boiling over. The auxiliary water pump works together with the puller and pusher fans to rapidly reduce the temperature of the coolant in the radiator. The auxiliary water pump only operates when the engine is shut off.

Heating and cooling systems are in integral part of today's automobiles, trucks, vans, and SUVs. And parts do occasionally wear out. These parts include the water pump, the heater core, the pusher and puller fans, the radiator, and the system controls. It is often fairly easy to work on these components and repair them yourself, saving time and money. Consult a printed or online repair manual should you decide to make interior heating system repairs yourself. And always remember: safety first