Passenger Compartment Air Temperature Control
The heat from the climate control coolant is transferred in the climate control assembly by the heater core to the passenger compartment air. The HVAC control module operates the blower and required flaps to control the air flow and temperature as required.
The HVAC also controls the Air Conditioning (A/C) system to cool the passenger compartment when required. The A/C system uses an A/C evaporator in the climate control assembly with an orifice tube to regulate the flow of refrigerant through the A/C evaporator. Cooled air from the A/C evaporator enters the climate control assembly. The HVAC controls the temperature blend doors to direct a proportion of the air through the heater core to produce the required output air temperature.
On vehicles with 2 or 4 zone climate control, the temperature blend doors operate independently to enable individual temperature settings of the passenger compartment. The temperature blend doors are operated by electric motors, which are controlled by the HVAC using Local Interconnect Network (LIN) messages. The temperature blend motors send position data back to the HVAC on the LIN.
The HVAC calculates the temperature blend motor positions required to achieve the selected temperature and compares it against the current position. If there is any difference, the HVAC signals the motors to adopt the new position.
Air temperature is controlled automatically unless maximum heating or maximum cooling is selected. When maximum heating or cooling is selected, a comfort algorithm in the HVAC adopts an appropriate strategy for air distribution, blower speed, and air source.
On the vehicles with 2 zone climate control, temperature control of 1 side of the passenger compartment can be compromised by the other side of the passenger compartment being set to a high level of heating or cooling. True maximum heating or cooling can only be selected from the driver side temperature control switch. If maximum heating or cooling is selected from the driver side, the passenger side temperature is automatically set to match the driver side. If the 'Sync' icon key on the Integrated Control Panel (ICP) is selected, the HVAC synchronizes the passengers settings with those of the driver.
When A/C is selected off, no cooling of the intake air occurs. The minimum output air temperature from the system is the ambient air temperature plus any heat pick up in the air intake path.