System Description

AUTOMATIC AIR CONDITIONING SYSTEM


System Description


OUTLINE
- Automatic air conditioner system is controlled by each function of A/C auto amp., ECM, BCM and IPDM E/R.

Control by A/C auto amp.
- Air outlet control
- Temperature control
- Air inlet control
- Air flow control
- Compressor control
- Door motor control (LCU communication control)

Control by BCM
- Compressor control

Control by ECM
- Cooling fan control. System Description.
- Air conditioning cut control. System Description.
- Compressor control

Control by IPDM E/R
- Relay control. With I-Key (WITH I-KEY) or Without I-Key (WITHOUT I-KEY).
- Cooling fan control. With I-Key (WITH I-KEY) or Without I-Key(WITHOUT I-KEY).
- Each A/C system can be operated by A/C controller (built-in A/C auto amp.).

OPERATION

Controller (A/C Control)
For USA










For Canada











Switch Operation











AIR OUTLET CONTROL





- While air outlet is in automatic control, A/C auto amp. selects the mode door position depending on a target air mix door angle and outlet air temperature calculated from sunload.
- If ambient temperature is excessively low, D/F is selected to prevent windshield fogging when air outlet is set to FOOT.

TEMPERATURE CONTROL





- When ignition switch is in the ON position, A/C auto amp. always automatically controls temperature regardless of air conditioner operational state.
- A/C auto amp. calculates the target air mix door opening angle depending on set temperature, in-vehicle temperature, ambient temperature, and sunload.
- Air mix door is controlled depending on the comparison of current air mix door opening angle and target air mix door opening angle.
- Regardless of in-vehicle temperature, ambient temperature, and sunload, air mix door is fixed at the fully cold position when set temperature is 18�C (60�F), and at the fully hot position when set temperature is 32�C (90�F).

AIR INLET FUNCTION





- While air inlet is in automatic control, A/C auto amp. selects air inlet (fresh air intake, 20% fresh air intake, or recirculation) depending on set temperature, in-vehicle temperature, and ambient temperature.
- Air inlet is fixed to 80% FRE, only when the conditions are satisfied as follows:
- Air inlet is FOOT or D/F
- Ambient temperature is 2�C (36�F) or less
- Maximum fan speed

AIR FLOW CONTROL

Description
- A/C auto amp. changes duty ratio of blower motor drive signal and controls air flow continuously. When air flow is increased, duty ratio of blower motor drive signal gradually increases to prevent a sudden increase in air flow.
- In addition to manual control and automatic control, air flow control is compose of starting fan speed control, low coolant temperature starting control, high in-vehicle temperature starting control, and blower speed control at door motor operation.

Automatic Air Flow Control
- A/C auto amp. decides target air flow depending on target air mix door opening angle.
- A/C auto amp. changes duty ratio of blower motor drive signal and controls air flow continuously so that air flow matches to target air flow.





- When air outlet is VENT or B/L, the minimum air flow is changed depending on sunload.

Starting Fan Speed Control
When blower motor is activated, A/C auto amp. gradually increases duty ratio of blower fan drive signal to prevent a sudden increase in discharge air flow. (T1 - T2 = approximately 10 seconds)





NOTE:
Do not perform the starting air flow control when the discharge outlet is set to DEF.

Low Coolant Temperature Starting Control





If the engine coolant temperature is 56�C (133�F) or less, to prevent a cold discharged air flow, A/C auto amp. suspends blower motor activation for the maximum 150 seconds depending on target air mix door opening angle. After this, blower fan drive signal is increased gradually, and blower motor is activated.

Fan speed Control at Door Motor Operation
When mode door motor is activated while air flow is more than the specified value, A/C auto amp. reduces temporarily fan speed so that mode door moves smoothly.

High In-vehicle Temperature Starting Control
When evaporator temperature is high [intake air temperature sensor value is 35�C (95�F) or more], to prevent a hot discharged air flow, A/C auto amp. suspends blower motor activation for approximately 3 seconds so that evaporator is cooled by refrigerant.

COMPRESSOR CONTROL

Description
- When the compressor activation condition is satisfied while blower motor is activated, A/C auto amp. transmits A/C ON signal and blower fan ON signal to BCM.
- BCM transmits A/C ON signal and blower fan ON signal to ECM via CAN communication.
- ECM judges that the compressor can be activated depending on each sensors state (refrigerant pressure sensor signal, throttle opening angle sensor signal, and others). And transmits A/C relay control signal to IPDM E/R via CAN communication.
- IPDM E/R turns A/C relay ON and activates the compressor depending on request from ECM.

Compressor Protection Control at Pressure Malfunction
When high-pressure side value that is detected by refrigerant pressure sensor is as per the following state, ECM requests IPDM E/R to turn A/C relay OFF and stops the compressor.
- 3.12 MPa (31.8 kg/cm2, 452 psi) or more (When the engine speed is less than 1,500 rpm)
- 2.74 MPa (27.9 kg/cm2, 397 psi) or more (When the engine speed is 1,500 rpm or more)
- 0.14 MPa (1.4 kg/cm2, 20 psi) or less

Compressor Oil Circulation Control
When the engine starts while the engine coolant temperature is 56�C (133�F) or less, ECM activates the compressor for approximately 6 seconds and circulates the compressor lubricant once.

Low Temperature Protection Control





When intake sensor detects that evaporator surface temperature is 2�C (36�F) or less, A/C auto amp. requests ECM to turn the compressor OFF, and stops the compressor.
When the air temperature returns to 3.5�C (38�F) or more, the compressor is activated.

Operating Rate Control
When set temperature is other than fully cold or air outlet is "VENT", "B/L" or "FOOT" A/C auto amp. controls the compressor activation depending on ambient temperature.

Air Conditioner Cut Control
When the engine is running in excessively high load condition, ECM requests IPDM E/R to turn A/C relay OFF, and stops the compressor. System Description for details.

DOOR MOTOR CONTROL

Mode Door Motor
The A/C auto amp. receives data from each sensors. When a drive signal is input from A/C auto amp. to door motor, a step motor built into the door motor rotates according to the drive signal, and then stops at the position of target door.






Air Mix Door Motor
The A/C auto amp. receives data from each sensors. When a drive signal is input from A/C auto amp. to door motor, a step motor built into the door motor rotates according to the drive signal, and then stops at the position of target door.






Intake Door Motor





The A/C auto amp. receives data from each sensor, and converts them to control signal. The A/C auto amp. sends the control signal to Intake door motor. When intake door motor receives the control signal, intake door is moved to appropriate position by PBR opening angle indication signal.

SWITCHES AND THEIR CONTROL FUNCTIONS
















AIR DISTRIBUTION