The heater core is the main component of the heater system. The heater core is located inside of the HVAC module. Engine coolant is pumped into the heater core from the engine whenever the engine is operating. The heater core fins transfers the heat from the engine coolant to the air passing over the heater core. The heater core has specific inlet and outlet tubes. The placement of the heater hoses should be noted prior to servicing the heater core or the heater hoses.
When the temperature control is commanded to the full COOL position, the mode door is held snugly against the air entrance to the heater core. The following actions occur:
| • | All of the airflow from the evaporator bypasses the heater core. |
| • | No heat transfer occurs. |
When the temperature control is commanded from the full COOL position, the air mix doors allow air to be directed to flow through the heater core. The warmer the temperature control is commanded, the more the air mix doors move to allow air to flow through the heater core.
