HVAC Control System Description

WARNING: This page is about a different car, the 2010 Suzuki Kizashi. However, it is still accessible from the selected car via links, so may be relevant.

Following data are sent from each control module to the HVAC control module through CAN communication. For CAN communication system, refer to description on COMMUNICATION SYSTEM DESCRIPTION .

Engine coolant temperature
Engine speed
A/C refrigerant pressure
Vehicle speed (wheel speed)
Outside air temperature
Evaporator temperature
A/C compressor clutch state

Based on above data, HVAC control module sends A/C compressor ON/OFF request signal to ECM through CAN communication.

Furthermore, when the defrost switch is turned on or the "MODE" (air flow) switch is selected to "D/F" mode, HVAC control module sends A/C compressor ON request signal to BCM through CAN communication to clear fog from windshield.

BCM sends this signal through CAN communication to ECM which then causes A/C compressor relay to turn ON/OFF.

For more information on signal transmission and reception of Auto A/C system, refer to HVAC ELECTRONIC CONTROL INPUT/OUTPUT BLOCK DIAGRAM .