ECO MODE - official info
4. Eco Mode Control
General Eco mode control limits the air conditioning system performance during heating and cooling and
increases the amount of engine OFF time, thus improving the fueleconomy. Eco mode control is activated by pressing the momentary type ECO switch on the instrument panel.
“ECO” is displayed on the heater control panel LCD during this control. Eco mode control during heating and cooling, and its cancel conditions are shown in the table below.

Heating Mode

Stops PTC heater operation.
Increases the amount of engine OFF time.
Prohibits BI-LEVEL mode during AUT operation.

Eco Mode Cancel Conditions

DEF or FOOT DEF mode is selected.
MAX HOT temp. setting
ECO switch OFF

Cooling Mode

Limits power consumption by the electric inverter compressor based on the room temperature.

Eco Mode Cancel Conditions

MAX COLD temp. setting
ECO switch OFF

Heating Mode
The required engine coolant temperature when starting the engine when the vehicle is stopped differs from that when the vehicle is running. Therefore, the fuel economy has been improved by increasing the amount of engine-off time when the vehicle is stopped.
When the ECO switch is turned ON during heating, the A/C ECU stops the PTC heater operation.Therefore, it takes a longer time to reach the set temperature than while the ECO switch is OFF
Engine coolant temperatures fluctuate greatly between when the vehicle is running and the vehicle is stopped. The blower level changes accordingly.

Cooling Mode
When the ECO switch is turned ON during cooling, the A/ C ECU limits the power consumption of the electric inverter compressor in accordance with the room temperature. The A/ C ECU does not limit the power consumption very much , and prioritizes decreasing the room temperature when the room temperature is high. When the room temperature decreases to or below, the A/ C ECU limits the power consumption of the electric inverter compressor and restrains the cooling performance. This prevents the SOC (state of charge) of the HV battery from decreasing and increases the amount of engine OFF time, improving the fuel economy.

NOTE: ECO mode control is performed only when the blower motor is ON. When the ECO switch is turned ON while the blower motor is OFF, the ECO switch indicator light and the heater control panel LCD display illuminate, but ECO mode control is not performed.
During cooling under ECO mode control, the room temperature is maintained at 25C (77F) even if the set temperature is below 25C (77F). Since the power consumption of the electric inverter compressor is limited under ECO mode control, this does not indicate a malfunction. To decrease the room temperature to below 25C (77F), the MAX COLD temperature [18C (64.4F)] must be selected or ECO mode control must be canceled by turning the ECO switch OFF.