A/C Identification Label
Vehicles with factory installed fluorescent dye have this identification label on the underside of hood.
Description
The front air control provides automatic regulation of the vehicle's interior temperature. The system is based on the driver's and passenger's selected "set temperature", regardless of the outside temperature changes. This is done by utilizing a microcomputer, also referred to as the front air control, which receives input signals from the following six sensors
- Ambient sensor
- In-vehicle sensor
- Intake sensor
- Optical sensor (providing one input for driver and one input for passenger side)
- PBR (Position Balanced Resistor)
- Vehicle speed sensor
The front air control uses these signals (including the set temperature) to automatically control
- Outlet air volume
- Air temperature
- Air distribution
The front air control also provides separate regulation of the vehicle's interior temperature for the rear passenger area. The system is based on the temperature and rear blower settings selected from rear control switches located on the front air control, or from the temperature and rear blower settings selected from rear control switches on the rear air control, when the front air control switches are set to the rear position.
The front air control is used to select
- Outlet air volume
- Air temperature/distribution
Description of Control System
The control system consists of input sensors, switches, the front air control (microcomputer) and outputs.
The relationship of these components is shown in the figure below
Identifying Wiring Diagram - ATC-AC,A-04. Scheme 2
Identifying Wiring Diagram - ATC-AC,A-05. Scheme 3
CAN Communication System Description
Refer to " SYSTEM DESCRIPTION ".
The self-diagnostic system diagnoses sensors, CAN system, battery voltage and stuck button on front air control. Refer to applicable articles (items) for details. Fault codes (if any are present) will be displayed in the ambient temperature display area (with navi) and displayed in the driver temp display area (without navi). Refer to " SELF-DIAGNOSIS CODE CHART ".
Identifying A/C System Self-Diagnosis Function Chart. Scheme 4
Operational Check (Front)
The purpose of the operational check is to confirm that the system operates properly.
Conditions : Engine running and at normal operating temperature
Operational Check (Rear)
The purpose of the operational check is to confirm that the system operates properly.
Conditions : Engine running and at normal operating temperature
System Operation
The mode door position (vent, B/L, foot, and defrost) is set by the front air control by means of the mode door motor. When a mode door position is selected on the front air control, voltage is applied to one circuit of the mode door motor while ground is applied to the other circuit, causing the mode door motor to rotate. The direction of rotation is determined by which circuit has voltage applied to it, and which one has ground applied to it. The front air control monitors the mode door position by measuring the voltage signal on the PBR circuit.
In AUTO mode the mode door position is set by the front air control which determines the proper position based on inputs from the in-vehicle sensor, ambient sensor, optical sensor, intake sensor, and the temperature selected by the driver or passenger.
Identifying Mode Door Position System Operation Diagram. Scheme 5
Identifying Mode Door Control Specifications Graph. Scheme 6
The front air control receives data from the temperature selected by the driver side, passenger side, and rear. The front air control then applies a voltage to one circuit of the appropriate air mix door motor, while ground is applied to the other circuit, causing the appropriate air mix door motor to rotate. The direction of rotation is determined by which circuit has voltage applied to it, and which one has ground applied to it. The front air control monitors the air mix door positions by measuring the voltage signal on the PBR circuits of each door.
In AUTO mode the air mix, intake, mode door, and defrost door positions are set by the front air control which determines the proper position based on inputs from the in-vehicle sensor, ambient sensor, optical sensor, intake sensor, and the temperature selected by the driver and front and rear passengers.
Subsequently, HOT/COLD or DEFROST/VENT or FRESH/RECIRCULATION operation is selected. The new door position data is returned to the front air control.
Identifying PBR Circuit Block Diagram. Scheme 7
Identifying Air Mix Door Angle Graph. Scheme 8
The intake door control determines the intake door position based on the position of the recirculation switch. When the recirculation switch is depressed the intake door motor rotates closing off the fresh air inlet and recirculating the cabin air. If the recirculation switch is depressed again, the intake door motor rotates in the opposite direction, again allowing fresh air into the cabin.
In the AUTO mode, the front air control determines the intake door position based on the ambient temperature, the intake air temperature and the in-vehicle temperature. When the DEFROST, or OFF switches are pushed or A/C switch is OFF, the front air control sets the intake door at the fresh position.
Scheme 9
Identifying Rear Blower Motor - Circuit Diagram. Scheme 10
SYSTEM DESCRIPTION
The front air control controls compressor operation based on ambient and intake temperature and a signal from ECM.
The heater pump improves heater performance specifically at idle conditions. It is designed to operate in either of the following 2 situations
Scheme 11
- Front blower motor set to maximum speed and temperature control dial (driver or passenger) set to full hot 32°C (90°F) or
- Engine coolant temperature (signal via CAN communication) minus heater core outlet temperature (intake sensor input to front air control) is greater than 20°C (68°F). If the difference is less than 16°C (61°F), the heater pump will not operate unless the conditions in item No. 1 above are met. see scheme 128: Identifying Heater Pump Circuit Diagram
Scheme 12
Scheme 13
Scheme 14
Scheme 15
Scheme 16
- CHECK POWER SUPPLY TO HEATER PUMP Disconnect heater pump connector. Turn ignition switch ON. Set front blower motor to maximum speed. Turn temperature control dial (passenger or driver) to full hot 32°C (90°F). Check voltage between heater pump harness connector E141 terminal 1 and ground. 1 - Ground: Battery voltage OK or NG OK: GO TO 2. NG: GO TO 3. see scheme 129: Checking Voltage Between Heater Pump Harness Connector E141 Terminal 1 And Ground
- CHECK HEATER PUMP GROUND Turn ignition switch OFF. Check continuity between heater pump harness connector E141 terminal 2 and ground. 2 - Ground: Continuity should exist. OK or NG OK: Replace heater pump. Refer to " «HEATER PUMP»(ref-272532-S36205140032007112100000) ". NG: Repair harness or connector. see scheme 130: Checking Continuity Between Heater Pump Harness Connector E141 Terminal 2 And Ground
- CHECK HEATER PUMP RELAY Turn ignition switch OFF. Check heater pump relay. Refer to " «HEATER PUMP RELAY»(ref-272532-S21840468072007112100000) ". OK or NG OK: GO TO 4. NG: Replace heater pump relay.
- CHECK RELAY POWER SUPPLY Turn ignition switch ON. Check voltage between heater pump relay harness connector E144 terminals 2, 5 and ground. 2 - Ground: Battery voltage 5 - Ground: Battery voltage OK or NG OK: GO TO 5. NG: Repair harness or connector. see scheme 131: Checking Voltage Between Heater Pump Relay Harness Connector E144 Terminals 2, 5 And Ground
- CHECK HEATER PUMP MOTOR POWER CIRCUIT Turn ignition switch OFF. Check continuity between heater pump relay harness connector (A) E144 terminal 3 and heater pump harness connector (B) E141 terminal 1. 3 - 1: Continuity should exist. Check continuity between heater pump relay harness connector (A) E144 terminal 3 and ground. 3 - Ground: Continuity should not exist. see scheme 132: Checking Continuity Between Harness Connector (A) E144 Terminal 3 And Connector (B) E141 Terminal 1 OK or NG OK: GO TO 6. NG: Repair harness or connector.
- CHECK CIRCUIT BETWEEN HEATER PUMP RELAY AND FRONT AIR CONTROL Disconnect front air control connector. Check continuity between front air control harness connector (A) M50 terminal 44 and heater pump relay harness connector (B) E144 terminal 1. 1 - 44: Continuity should exist. Check continuity between heater pump relay harness connector (B) E144 terminal 1 and ground. 1 - Ground: Continuity should not exist. see scheme 133: Checking Continuity Between Harness Connector (A) M50 Terminal 44 And Connector (B) E144 Terminal 1 OK or NG OK: Replace front air control. Refer to " «FRONT AIR CONTROL»(ref-272532-S28821507462007112100000) ". NG: Repair harness or connector.
COMPONENT DESCRIPTION
The optical sensor is located in the center of the defroster grille. It detects sunload entering through windshield by means of a photo diode. The sensor converts the sunload into a current value which is then input into the front air control.
Identifying Front Heater And Cooling Unit Assembly Components With Torque Specification. Scheme 17
BREAK-IN OPERATION
When replacing compressor clutch assembly, always conduct the break-in operation. This is done by engaging and disengaging the clutch about 30 times. Break-in operation raises the level of transmitted torque.