Overview
The Dual Automatic Temperature Control (DATC) system maintains the selected vehicle interior temperature by heating and/or cooling the air depending on the HVAC control panel selection.
- The driver may override the automatic mode of operation.
- The temperature control setting is the desired cabin air temperature.
- The blower motor control override buttons vary the blower motor speed.
- The driver side and passenger side temperature settings can be individually controlled.
- During A/C operation, the system reduces the relative humidity of the air inside the vehicle.
HEV is equipped with an Exhaust Manifold and Catalytic Converter Assembly with coolant passages to heat engine coolant more rapidly, speeding up passenger compartment heating in cold temperatures.
Scheme 1
Controls and Compressor Operation
Climate control commands are input through the HVAC control module. On vehicles equipped with Sony® Sound inputs can also be commanded through voice commands or the touch screen.
When the A/C is requested, the HVAC control module sends the message over the Medium Speed Controller Area Network (MS-CAN) to the GWM . The GWM then forwards the message to the PCM over the High Speed Controller Area Network (HS-CAN).
An A/C demand message is sent from the PCM over the High Speed Controller Area Network (HS-CAN) to the ACCM when all of the following conditions are met
- The PCM does not detect excessively high or low refrigerant pressure from the A/C pressure transducer.
- The PCM does not detect an ambient air temperature below approximately 35.6°F (2°C).
- The PCM does not receive a message from the BCM detecting an evaporator discharge air temperature below approximately 35.6°F (2°C).
The ACCM engages when it receives the A/C demand message and target Revolutions Per Minute (RPM) request. Instead of cycling on and off like a traditional A/C electric compressor, the PCM monitors the evaporator discharge temperature from the HVAC control module to raise or lower the A/C electric compressor speed as required.
The HVAC control module adjusts the air inlet door depending on the humidity measured by the in-vehicle temperature and humidity sensor. If the vehicle cabin becomes too humid and recirculated air is selected, the HVAC control module adjusts the air inlet door to allow more fresh air. When the humidity level drops, it may adjust back to partial recirculated air. The HVAC control module also adjusts the system based on in-vehicle temperature.
The sunload sensor supplies information to the HVAC control module indicating the intensity of the sun on the vehicle. The HVAC control module adjusts the system based on the intensity.
Normal operation and Fault Conditions
The A/C pressure transducer receives a ground from the PCM . A 5-volt reference voltage is supplied to the A/C pressure transducer from the PCM . The A/C pressure transducer then sends a voltage to the PCM to indicate the A/C pressure.
The ACCM requires an operating voltage between 9 and 16 volts. The ACCM receives this voltage from the BJB . The ACCM has a single ground circuit located in the engine compartment wiring harness. Excessive resistance or an open in one or more of these circuits, a discharged battery or an inoperative charging system results in the ACCM setting a DTC .
Control System Logic
REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION (412-00 Climate Control System - General Information, Description and Operation).
Control System Logic
REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION (412-00 Climate Control System - General Information, Description and Operation).
System Operation
REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION (412-00 Climate Control System - General Information, Description and Operation).
Actuator - Air Inlet Door
REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION (412-00 Climate Control System - General Information, Description and Operation).
During an actuator calibration cycle, the HVAC control module drives the air inlet door until the door reaches both internal stops in the HVAC case. If the air inlet mode door is temporarily obstructed or binding during a calibration cycle, the HVAC control module may interpret this as the actual end of travel for the door. When this condition occurs and the HVAC control module commands the actuator to its end of travel, the air intake may not be from the expected source.
During an actuator calibration cycle, the HVAC control module drives the defrost vent/register door or the footwell vent door until the door reaches the internal stops in the HVAC case. If either mode door is temporarily obstructed or binding during a calibration cycle, the HVAC control module may interpret this as the actual end of travel for the door. When this condition occurs and the HVAC control module commands the actuator to its end of travel, the airflow may not be from the expected outlets.
When the engine is at operating temperature hot coolant flows from the electric motor through the heater core and back to the electric motor. Correct coolant temperatures are critical for good heater performance.
Control System Logic
REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION (412-00 Climate Control System - General Information, Description and Operation).
Controls and Compressor
REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION (412-00 Climate Control System - General Information, Description and Operation).
A/C pressure transducer
REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION (412-00 Climate Control System - General Information, Description and Operation).
Evaporator Temperature Sensor
REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION (412-00 Climate Control System - General Information, Description and Operation).
Control System Logic
REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION (412-00 Climate Control System - General Information, Description and Operation).
Controls and Compressor Operation
REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION (412-00 Climate Control System - General Information, Description and Operation).
A/C pressure transducer
REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION (412-00 Climate Control System - General Information, Description and Operation).
Evaporator Temperature Sensor
REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION (412-00 Climate Control System - General Information, Description and Operation).
Control System Logic
REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION (412-00 Climate Control System - General Information, Description and Operation).
Controls and Compressor Operation
REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION (412-00 Climate Control System - General Information, Description and Operation).
A/C pressure transducer
REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION (412-00 Climate Control System - General Information, Description and Operation).
Evaporator Temperature Sensor
REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION (412-00 Climate Control System - General Information, Description and Operation).
Temperature Door Actuator - Driver Side
REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION (412-00 Climate Control System - General Information, Description and Operation).
During an actuator calibration cycle, the HVAC control module drives the temperature door until the door reaches both internal stops in the HVAC case. If the temperature door is temporarily obstructed or binding during a calibration cycle, the HVAC control module may interpret this as the actual end of travel for the door. When this condition occurs and the HVAC control module commands the actuator to its end of travel, the airflow may not be the expected temperature.
Temperature Door Actuator - Passenger Side
REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION (412-00 Climate Control System - General Information, Description and Operation).
During an actuator calibration cycle, the HVAC control module drives the temperature door until the door reaches both internal stops in the HVAC case. If the temperature door is temporarily obstructed or binding during a calibration cycle, the HVAC control module may interpret this as the actual end of travel for the door. When this condition occurs and the HVAC control module commands the actuator to its end of travel, the airflow may not be the expected temperature.
Voltage is supplied to the blower motor relay from the BJB . When the blower motor relay coil receives a ground from the BCM , the relay coil is energized and voltage is delivered to the blower motor control module. and ground for the blower motor is provided by the blower motor speed control. The HVAC control module sends a PWM signal to the blower motor speed control to control the blower speed.
Voltage is supplied to the blower motor relay from the BJB . When the blower motor relay coil receives a ground from the BCM, the relay coil is energized and voltage is delivered to the blower motor control module and ground for the blower motor is provided by the blower motor speed control. The HVAC control module sends a PWM signal to the blower motor speed control to control the blower speed.
The 4 air discharge temperature sensors contain a thermistor. The sensor varies its resistance with the temperature. As the temperature rises, the resistance falls. As the temperature falls, the resistance rises.
In-Vehicle Temperature and Humidity Sensor
REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION (412-00 Climate Control System - General Information, Description and Operation).
Sunload Sensor
REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION (412-00 Climate Control System - General Information, Description and Operation).
The HVAC control module requires an operating voltage between 9 and 16 volts. The HVAC control module receives this voltage from the BJB . The HVAC control module has a single ground circuit located in the engine compartment wiring harness. Excessive resistance or an open in one or more of these circuits, a discharged battery or an inoperative charging system results in the HVAC control module setting a DTC .
Control System Logic
REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION (412-00 Climate Control System - General Information, Description and Operation).
Evaporator Temperature Sensor
REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION (412-00 Climate Control System - General Information, Description and Operation).
Control System Logic
REFER to: CLIMATE CONTROL SYSTEM - SYSTEM OPERATION AND COMPONENT DESCRIPTION (412-00 Climate Control System - General Information, Description and Operation).
HEV is equipped with an exhaust manifold and catalytic converter assembly with coolant passages. It is used to heat engine coolant more rapidly, speeding up passenger compartment heating. This system includes an ECT sensor 2 (also known as cabin heater coolant temperature sensor) on the coolant tube that is hardwired to the PCM . When low, high or erratic voltage is sensed by the PCM on the ECT sensor 2 circuit, a DTC is set.