Climate Control System
When AUTO mode is activated and set temperature is at or between 66°F (18.5°C) and 89°F (31.5°C), the following are automatically controlled depending on ambient temperature, cabin temperature, sunlight intensity, and set temperature:
- four vent modes
Max-cool mode is activated in AUTO mode when 65°F (18.0°C) is selected. In max-cool mode...
- dash vent mode is selected
Max-warm mode is activated in AUTO mode when 90°F (32.0°C) is selected. In max-warm mode...
- floor vent mode is selected
Manual Control Functions
When a manual override button is pressed, the AUTO light is extinguished indicating that manual control has been activated for that function. Other functions not selected will continue to operate in full-automatic or semi-automatic mode unless also selected. Settings are saved between key cycles (unless battery power is lost).
Manual Override Buttons
Overrides automatic control of vent mode function and cycles through four vent modes.
dash and floor floor defog and floor dash
Overrides automatic 32-speed fan operation and cycles through four fixed speeds.
low med-low med-high max-high
Overrides automatic control of A/C function and cycles through three modes.
A/C economy A/C off A/C normal
Overrides automatic three-position air intake control and cycles through two manual positions.
fresh air recirculated air
Windshield Defogging Operation
When activated, airflow is sent to the defogger and side dash vents, fan speed is increased, A/C function is activated if ambient temperature permits, and fresh air intake mode is set to rapidly clear the windshield and side windows of frost or fog. A second press returns the system to the previous mode. When defog mode is activated in AUTO mode, the AUTO indicator is extinguished.
Ambient Temperature Display
When pressed, the ambient temperature is displayed in place of the set temperature. Pressing the AMB button a second time or using the temperature selection control will return the display to the set temperature.
AUTO Mode - Full Automatic Vent, Fan, & A/C Control Examples
77°F (or 25.0°C) is the default set temperature. With the default set temperature selected in AUTO mode, the following examples are representative of typical vent modes, fan speeds, and A/C modes once cabin temperature has stabilized to the set temperature under average conditions. Modes will vary from these examples depending on sunlight intensity, current cabin temperature, and vehicle speed.
At temperatures well below freezing, floor vent mode is activated and A/C operation is disabled. Warm-up correction logic inhibits fan speed and defog/floor vent mode is activated until engine coolant temperature has risen sufficiently to prevent cold air from being blown through the floor vents. Fresh air mode is activated while fan speed and heater core air mix are altered continuously depending on sunlight intensity, cabin temperature, and vehicle speed.
For temperatures at or near freezing, A/C mode is activated and heater core air-mix is continually adjusted to dehumidify the cabin air and prevent window fogging while maintaining the cabin set temperature. Warm-up correction logic inhibits fan speed and modifies vent mode until heater core temperature has risen sufficiently to prevent cold air from being blown into the cabin. Floor/defog vent mode may be activated intermittently along with floor vent mode, or continuously in order to improve defogging performance depending on conditions.
In cool conditions, A/C mode is activated and heater core air-mix is continually adjusted to dehumidify the cabin air and prevent window fogging while maintaining the cabin set temperature. In dash/floor vent mode, cooler air that approximates the set temperature may be blown from one or more dash vents while warmer air is sent to the floor vents and other dash vents to regulate cabin temperature and maximize interior comfort.
At temperatures at or near the set temperature, A/C mode is activated and heater core air mix is adjusted to dehumidify cabin air while cabin temperature is maintained. Fan speed is altered depending on sunlight intensity to maintain optimum interior comfort and ventilation while maximizing A/C efficiency. Fresh air intake mode is activated and airflow is directed exclusively in dash vent mode and from the defroster vents to prevent the outside of the windshield from fogging.
Under hot conditions, A/C mode is activated, fan speed is increased, dash vent mode is selected, and the intake air actuator is positioned to allow two-thirds recirculated cabin air and one-third fresh air through the condenser unit to optimize cooling efficiency while maintaining continuous fresh air flow into the cabin. Immediately after engine start, and after being parked in the sun, hot start correction logic inhibits the fan speed for five seconds, then slowly raises fan speed as the condenser cools to prevent hot air from being blown into the cabin.
Max-hot & max-cold
Window frost prevention
The following trouble codes can only be read using a special service tool designed to interface with the A/C control system through the diagnostic port and are provided for informational purposes.
DTC02 - Solar radiation sensor malfunction (present code)
DTC06 - Passenger compartment temperature sensor malfunction (present code)
DTC07 - Passenger compartment temperature sensor malfunction (past code)
DTC10 - Evaporator temperature sensor malfunction (present code)
DTC11 - Evaporator temperature sensor malfunction (past code)
DTC12 - Ambient temperature sensor malfunction (present code)
DTC13 - Ambient temperature sensor malfunction (past code)
DTC14 - Engine coolant temperature sensor malfunction (present code)
DTC15 - Engine coolant temperature sensor malfunction (past code)
DTC18 - Air-mix actuator malfunction (present code)
DTC19 - Air-mix actuator malfunction (past code)
DTC21 - Airflow mode actuator malfunction (present code)
DTC22 - Airflow mode actuator malfunction (past code)
DTC58 - Air-mix actuator - lock (past code)
DTC59 - Airflow mode actuator - lock (past code)
[Mazda Millenia climate control diagnostic and trouble codes - From 2002 Mazda Millenia factory service manual]