Heating and Defrosting

HEATING AND VENTILATION

The heating and ventilation system operates as follows:
- Controls the temperature and during climate control operation, reduces the relative humidity of the air inside the vehicle.
- Delivers heated or cooled air to maintain the vehicle interior temperature and comfort level.
- The blower motor draws either outside or inside air through the air inlet duct from just below the windshield depending on the mode selected.
- All airflow from the blower motor passes through the A/C evaporator core.
- The temperature is then regulated by reheating a portion of the air and blending it with the remaining cool air to the desired temperature.
- The temperature blending is varied by the temperature blend door, which regulates the amount of air that flows through and around the heater core, where it is then mixed and distributed.

Heater Core and Evaporator Core Housing
The heater core and evaporator core housing is located behind the instrument panel between the air inlet duct and heater air plenum chamber.

The A/C evaporator housing assembly contains the following major components:
- A/C evaporator core
- heater core
- air distribution doors

Heater Core
The heater core consists of fins and tubes arranged to extract heat from the engine coolant and transfer it to air passing through the heater core.

Blower Motor
The blower motor pulls air from the A/C air inlet duct and forces it into the A/C evaporator housing where it is mixed and distributed.

Heater Hoses
The heater hoses are made of rubber hose and metal tube assemblies that are connected together using aluminum clamps that are crimped into place. The aluminum clamps must not be removed. The heater hoses are not serviced as subassemblies by separating the rubber hoses from the metal tubes. The heater core inlet hose and the heater core outlet hose are two separate assemblies.