Heater Unit Description

WARNING: This page is about a different car, the 2002 Mazda 626. However, it is still accessible from the selected car via links, so may be relevant.

The heater regulates the airflow mode and the outlet airflow temperature.

Heater core operation

A portion of engine coolant is diverted to the inside of the heater core, where it heats the air passing through the core.

Fig 1: Identifying Heater Core & Radiator Coolant Flow
Courtesy of MAZDA MOTORS CORP.

Air mix door operation

The air mix doors, installed in the heater unit, move to each position: HOT or COLD, by the air mix actuator's operation. As a result, airflow distribution changes.

Fig 2: Identifying MAX HOT & MAX COLD Air Mix Door Positions
Courtesy of MAZDA MOTORS CORP.

Airflow mode door operation

The airflow mode doors, installed in the heater unit, move to each position: VENT, BI-LEVEL, HEAT, HEAT/DEF, DEFROSTER, by the airflow mode actuator's operation. As a result, airflow mode changes.

Fig 3: Identifying VENT, BI-LEVEL & HEAT Airflow Mode Door Positions
Courtesy of MAZDA MOTORS CORP.

Fig 4: Identifying HEAT/DEF & DEFROSTER Airflow Mode Door Positions
Courtesy of MAZDA MOTORS CORP.

Airflow distribution

Fig 5: Airflow Mode Distribution Percentages Table
Courtesy of MAZDA MOTORS CORP.