The climate control unit performs the following controls based on the signals from each switch/dial and the sensor.
Airflow temperature control
Airflow volume control
Airflow mode control
Air intake control
A/C compressor control
Controls the A/C operation by switching the A/C relay on/off at the optimal timing according to engine operation conditions. (See A/C CUT-OFF CONTROL [SKYACTIV-G 2.5].)
The manual air conditioner system functions based on the five basic types of controls and three supplementary functions.
| Control name | Control part |
| Climate control unit |
| Supplementary function |
| Fail-safe function |
| Sensor signal delay function |
| On-board diagnostic function |
When the engine is restarted after being temporarily stopped, the ambient temperature sensor may detect a temperature higher than the actual ambient temperature.
To prevent this, if the engine coolant temperature exceeds 55 °C {131 °F}, control of each system is performed based on the ambient temperature data before the engine was stopped, which is stored in the climate control unit.
The climate control unit drives the air mix actuator according to the operation of the temperature setting dial.
The air mix actuator changed the air mix door position.
When the temperature control dial is set to the MAX COLD position, the climate control unit performs the MAX A/C control (when the airflow mode is VENT or BI-LEVEL).
The MAX A/C control controls the air conditioner as follows:
Sets the intake mode to REC.
Turns on the A/C compressor.
The climate control unit changes the blower motor applied voltage (airflow volume) in seven steps according to the operation of the airflow volume control dial.
| Airflow volume control dial | Blower motor applied voltage |
| 1st | 3.7 V |
| 2nd | 5.2 V |
| 3rd | 6.9 V |
| 4th | 8.6 V |
| 5th | 10.0 V |
| 6th | 12.1 V |
| 7th | 14.6 V*1, 13.0V*2 |
The start-up burn-out prevention function prevents the blower motor from being burnt out because of excess current.
When the blower motor is started-up from the stopped status with a blower motor applied voltage of 4.4 V or more, the blower motor applied voltage is fixed at 4.4 V for 1 s.
When the blower motor rotation exceeds and rises above the blower motor applied voltage from a low speed condition, the delay control delays the blower motor applied voltage for approx. 1 s and stabilizes the motor operation.
The climate control unit switches the airflow mode based on the MODE switch operation.
| Airflow mode | Operation switch | Air vent |
| VENT | Mode switch | CENTER VENT, SIDE VENT |
| BI-LEVEL | CENTER VENT, SIDE VENT, FRONT HEAT, REAR HEAT |
|
| HEAT | FRONT HEAT, REAR HEAT, SIDE DEMISTER (low volume), DEFROSTER (low volume), SIDE VENT (low volume) |
|
| DEF/HEAT | FRONT HEAT, REAR HEAT, SIDE DEMISTER, DEFROSTER, SIDE VENT (low volume) |
|
| DEFROSTER | DEFROSTER switch | SIDE DEMISTER, DEFROSTER, SIDE VENT (low volume) |
The climate control unit switches the air intake mode based on the REC/FRESH switch operation.
| Air intake mode | REC switch operation |
| FRESH | Fixed to FRESH when the FRESH switch is turned on during REC mode |
| REC | Fixed to REC when the RECIRCULATE switch is turned on during FRESH mode |
The defroster control improves the defrosting effect.
When the defroster switch turns on, the climate control unit fixes the air intake mode to FRESH.
The air intake is fixed at FRESH even if it has been set to REC manually.
When the vehicle is driven at a very low speed with the A/C on under a severe heat condition, the climate control unit may change the air intake mode from FRESH to REC automatically.
Due to this, load to the A/C compressor is reduced.
When the air intake mode is switched to REC, the indicator on the REC switch illuminates.
The climate control unit sends the A/C signal to the PCM based on the signals sent from the A/C switch, airflow volume control dial, and evaporator temperature sensor.
The PCM turns the A/C relay on/off based on the input signals from the A/C signal and A/C pressure sensor and controls the A/C compressor (magnetic clutch) operation.
When the A/C switch and fan switch are turned on, the climate control unit turns the A/C signal (magnetic clutch) on/off based on the temperature of the air passing through the evaporator.
When the fan switch and A/C switch are turned on, the climate control unit controls the surface temperature of the evaporator so that it is within a certain range to prevent the evaporator from freezing.
When the ambient temperature is low, the climate control unit sets the A/C signal (magnetic clutch) off-temperature to low to prevent window fogging.