A/C System Description

The air conditioning system regulates temperature air outlet by mixing cold and warm air in an appropriate ratio. The heater core and evaporator core are installed in the heater unit that has the air mix control damper and the mode control damper. The blower unit is composed of a blower motor, the recirculation control damper and the dust and pollen filter. The blower unit is connected to the heater unit by the duct integral with the blower unit.

System Diagram

Air Flow Diagram

NOTE: This illustration is an example only. Appearance and structure of the actual parts may vary depending on the model.

Refrigerant Cycle

NOTE: This illustration is an example only. Appearance and structure of the actual parts may vary depending on the model.

Climate Control

The climate control system transmits appropriate signals to each motor based on the information (sunlight, humidity, in-car temperature, outside air temperature) received from each sensor. See below for details.

	Air Mix Control Motor: The system controls the temperature of air coming into the cabin by the air mix control motor adjusting the air mix control damper position in order to change the mixing ratio of warm and cold air.
	Mode Control Motor: The system directs the airflow to the specified area by the mode control motor switching the mode control damper position to the "VENT", "HEAT/VENT", "HEAT", "HEAT/DEF", or "DEF".
	Recirculation Control Motor: The recirculation control motor switches the recirculation control damper position to the “FRESH” or “RECIRCULATION”.
	BLOWER MOTOR: The blower motor changes the air volume based on the voltage adjusted by the blower power transistor.

The climate control unit optimizes these controls in order to maintain passenger comfort.

Relationship Between Vent (Air Outlet) Temperature and Actual In-Car Temperature

The climate control unit can automatically control vent temperature (air mix position), blower motor speed, blower intake, and A/C compressor operation to raise or lower the vehicle's interior temperature to match the customer's setting temperature. The actual vent outlet temperature largely depends upon the difference between the in-car temperature sensor reading and the customer's setting temperature.

Warm-Up Control

If heating is desired, and there is no available heat due to low engine coolant temperature, the climate control unit will slow the fan speed to avoid ventilating cold air. The climate control unit will gradually increase the fan speed as the engine coolant temperature rises.

The conditions that this control becomes effective are as follows:

	Fan speed "AUTO"
	Air outlet position "AUTO", "HEAT", or "HEAT/DEF"
	Outside air temperature is less than 68 °F (20 °C)
	Engine coolant temperature sensor is normal.
	Engine coolant temperature is less than 131 °F (55 °C)

Low Engine Coolant Temperature Control

When the engine coolant temperature is low, the climate control system changes an air outlet position to the "DEF". When the engine coolant temperature increases, the climate control system controls the air outlet position and outlet air temperature automatically.

Relationship Between Vehicle Speed and Blower Intake Mode

Because the air resistance is different between fresh air and recirculated air, the volume of air coming through the vents would be different if the fan speed was constant. When the recirculation control damper is set to "FRESH", the fresh air flow increases as the vehicle speed increases. The climate control unit regulates the fan speed so that the air volume is the same when "FRESH" or "RECIRC" mode is selected.

A/C Control

To prevent the evaporator from freezing, the climate control unit switches the A/C compressor ON and OFF based on the evaporator temperature sensor value. While in the automatic operation mode, the climate control unit automatically varies the A/C compressor operation time based on the evaporator temperature sensor value, as well as the outside air temperature.

MAX Control

When the temperature setting is adjusted to "MAX COOL (Lo)" or "MAX HOT (Hi)", the climate control unit overrides automatic control and defaults to the following operation:

	MAX COOL "RECIRC", "VENT", blower fan maximum speed, and A/C system ON.
	MAX HOT "FRESH", "HEAT", blower fan maximum speed, and A/C system ON. : If the sensor information indicates that the windshield may fog, the air outlet switches to "HEAT/DEF" automatically.

Customize Function

How to Change the Set Temperature (Climate Control Panel with Display)

The climate control unit has a function to change the set temperature +2.7 °F (+1.5 °C) or -2.7 °F (-1.5 °C) in case customers feel the temperature is too warm or too cold for the displayed temperature.

NOTE: Verify that the climate control and A/C system is working properly before enabling the customize function to offset the set temperature.

1.	Turn the vehicle to the ON mode, then based on the desired temperature change, set the temperature condition on the temperature control dial according to the table.
2.	Turn the climate control system OFF then turn the vehicle to the OFF (LOCK) mode.
3.	Depending on desired setting change, press and hold the pair of buttons according to the table.
4.	While holding the buttons, turn the vehicle to the ON mode.
5.	Keep the buttons pressed for 10 seconds.

Setting	Temperature Condition
+2.7 °F (+1.5 °C) Change	Hi	or
-2.7 °F (-1.5 °C) Change	Lo	or
Changing back to 0 °F (0 °C)	Except Hi or Lo	or

Indication of the change

The climate control unit displays the following during each change.

?	Displays nothing from the vehicle ON mode for 5 seconds.
?	Blinks the current setting for the next 5 seconds.
?	The display will indicate a Hi, Lo or two dashes depending on the set temperature change.

How to Change the Set Temperature (Climate Control Panel without Display)

NOTE: Verify that the climate control and A/C system is working properly before enabling the customize function to offset the set temperature.

The setting temperature is only displayed in degrees centigrade (°C).

1.	Turn the vehicle to the ON mode, then turn the vehicle to the OFF (LOCK) mode after confirming the climate control system is OFF.
2.	Press and hold the pair of buttons according to the table.
3.	While holding the buttons, turn the vehicle to the ON mode.
4.	Release the buttons, then select the desired temperature shift icon on the display.

Buttons
		or

NOTE: This illustration is an example only. Appearance and structure of the actual parts may vary depending on the model.

How to cancel A/C User Customizing

?	Turn the vehicle to the OFF (LOCK) mode.