Heater Core: Description and Operation

HEATER CORE

SYSTEM OPERATION

Combination Coil

Models equipped with the optional rear heater-A/C unit have a combination coil located within the rear unit housing. It is called a combination coil because it combines the functions of a heater core and an evaporator coil into a single heat exchanger unit.

The combination coil features six rows of tube and fin construction. The two rows located toward the outboard side of the vehicle serve as the heater core and have engine coolant circulated through them whenever the rear water valve is open. The four rows toward the inboard side of the vehicle serve as the evaporator and have refrigerant circulated through them whenever the air conditioning compressor is operating. The amount of refrigerant flowing through the combination coil is controlled by a dedicated rear thermal expansion valve.

The combination coil can be accessed for service by removing the rear heater-A/C unit upper housing. The combination coil cannot be repaired and, if faulty or damaged, it must be replaced.

Heater Core

Front

The heater core is located in the heater-A/C housing, on the right side of the engine compartment. It is a heat exchanger made of rows of tubes and fins. Engine coolant is circulated through heater hoses to the heater core whenever the front water valve is open. As the coolant flows through the heater core, heat removed from the engine is transferred to the heater core fins and tubes.

Air directed through the heater core picks up the heat from the heater core fins. The blend air door allows control of the heater output air temperature by controlling how much of the air flowing through the heater-A/C housing is directed through or around the heater core. The blower motor speed controls the volume of air flowing through the heater-A/C system.

The heater core cannot be repaired and, if faulty or damaged, it must be replaced.

Rear

Models equipped with the optional rear heater-A/C unit have a combination coil located within the rear unit housing. The combination coil functions as both the rear heater core and the rear evaporator coil. See Combination Coil above for more information.