HVAC Control System Description

HVAC Control System Description

When following data are sent from control modules to BCM through CAN communication, they are sent from BCM to HVAC control module through serial communication line. For CAN communication system, refer to description on CAN Communication System Description.
- Engine coolant temperature
- Engine speed
- A/C refrigerant pressure
- Vehicle Speed (wheel speed)
- Outside air temperature
Based on above data, HVAC control module sends A/C compressor ON / OFF request signal to BCM through serial communication line.
BCM sends this signal through CAN communication to ECM which then causes compressor relay to turn ON / OFF.
For more information on signal transmission and reception of Auto A/C system, refer to Auto A/C Electronic Control Input / Output Table.
HVAC control module has a function to make initial settings of temperature control actuator, air intake actuator and air flow actuator.
Initial settings of actuators are automatically made when engine is started for the first time after battery is connected.
When initial settings are made, each actuator is forced to operate for about 15 seconds continuously.