Climate Control System

Climate Control System

The system consists of the following components:

- Air Conditioning Compressor Module (ACCM)

- A/C condenser core

- A/C evaporator core

- Receiver/drier

- Connecting refrigerant lines

- Thermostatic Expansion Valve (TXV)

- A/C pressure transducer

- Heater core and evaporator core housing

- HVAC module

- Front Controls Interface Module (FCIM) (all vehicles equipped with navigation systems)

- Audio Control Module (ACM) (all vehicles equipped with navigation systems)

- Temperature blend door actuators

- Defrost/panel/floor mode door actuator

- Air inlet mode door actuator

- Blower motor speed control

- Blower motor

- Ambient air temperature sensor

- In-vehicle temperature/humidity sensor

- Sunload sensor

- Evaporator temperature sensor

Humidity Sensor

The humidity sensor is used by the HVAC module to optimize the Air Conditioning Compressor Module (ACCM) operation for reduced electrical system load while maintaining passenger comfort.

When the relative humidity inside the vehicle is low, passengers are comfortable at a higher air temperature. The ACCM (Air Conditioning Compressor Module) can decrease the compressor rpm before the commanded temperature is reached to reduce compressor electrical load while maintaining passenger comfort.

Hybrid Climate Control System Operation

NOTE: For the passenger side temperature setting on hybrid vehicles equipped with dual-zone Electronic Automatic Temperature Control (EATC) and a Front Controls Interface Module (FCIM) built on or after 4/08/2009 to be functional, a passenger must be seated in the front passenger seat. If the front passenger seat is not occupied, the HVAC module will control the system based only on the driver side temperature setting. The HVAC module receives a Medium Speed Controller Area Network (MS-CAN) signal from the FCIM (Front Controls Interface Module) to indicate if the front passenger seat is occupied.

When an A/C request is made by the HVAC module, a message is sent from the HVAC module over the Medium Speed Controller Area Network (MS-CAN) bus to the Instrument Cluster (IC) , then from the IC (Instrument Cluster) through the High Speed Controller Area Network (HS-CAN) bus to the PCM.

When an A/C request is received from the HVAC module, an A/C demand message is sent from the PCM over the HS-CAN (High Speed Controller Area Network) bus to the Air Conditioning Compressor Module (ACCM) if 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 excessively high engine coolant temperature.

- The PCM does not detect an ambient air temperature below -1°C (30°F).

- The PCM has not detected a Wide Open Throttle (WOT) condition.

- The HVAC module does not detect an evaporator discharge air temperature below 2°C (36°F).

When the ACCM (Air Conditioning Compressor Module) receives the A/C demand message, it will engage. Instead of cycling ON and OFF like a traditional A/C compressor, the PCM monitors the evaporator discharge temperature from the HVAC module to raise or lower the electric A/C compressor speed as required. When the HVAC module is OFF or not requiring A/C operation, the electric A/C compressor will be OFF.

Auxiliary Coolant Flow Pump

An auxiliary coolant flow pump is used only on hybrid vehicles to improve engine coolant circulation, for heater operation, at low engine speeds or when the engine is OFF.

For a complete explanation of the auxiliary coolant flow pump refer to heating and ventilation in the Description and Operation portion of Heating and Air Conditioning.