Controlling The Climate In The Passenger Compartment

The way in which the climate in the passenger compartment is regulated depends on the type of climate control module (CCM) in the car.

Electronic climate control 

Electronic climate control means that either manual settings or the AUTO function can be used. In the latter case the control module automatically regulates heat, air conditioning, recirculation and air distribution until the selected temperature is achieved.

Manual climate control 

Manual climate control means that heat, air conditioning, recirculation and air distribution must be selected manually.

STD 

STD means that heat, recirculation and air distribution must be selected manually.

The climate control module (CCM) (3/112) regulates the following:

• Activation of the air conditioning (A/C) compressor (8/3) with a request via the Controller area network (CAN) to the engine control module (ECM) (4/46)
• Controlling the damper motors. For electronic climate control (6/48), (6/95), (6/96), (6/102) and (6/103). For manual climate control; (6/48), (6/69), (6/95) and (6/96)
• Blower fan speed (6/28).

The climate control module (CCM) regulates the climate in the passenger compartment based on the following input signals:

• The passenger compartment temperature, signal from the internal passenger compartment temperature sensor
• The outside temperature, signal from the outside temperature sensor (7/11)
• The evaporator temperature, signal from the evaporator temperature sensor (7/41)
• Sun roof status. Signal from the sun roof control module (4/33) via the upper electronic module (UEM) (4/70) over the Controller area network (CAN)
• Side window status. Signals from the driver door module (DDM) (3/126) and passenger door module (PDM) (3/127) via the Controller area network (CAN)
• Door status. Signal from the central electronic module (CEM) (4/56) via the Controller area network (CAN)
• Sun intensity. Signal from the sun sensor (7/12)
• Speed. Signal from the brake control module (BCM) (4/16) (previously ABS), via the Controller area network (CAN)
• Windshield wiper status. Signal from the steering wheel module (SWM) (3/130) via the Controller area network (CAN).

The climate control module (CCM) (for electronic climate control) uses information about the status of the sun roof, side windows and doors to determine how it should compensate for changes in the passenger compartment temperature. If side windows, doors or the sun roof are opened, the climate control module (CCM) will not compensate for a change in passenger compartment temperature. Instead it maintains the same level of climate control for the compressor and blower fan as before.

The climate control module (CCM) (for electronic climate control) uses the signal from the steering wheel module (SWM) to establish whether the windshield wipers are switched on. This is to regulate the blower fan and the damper motor to remove any mist from the inside of the windshield when it rains.

The climate control module (CCM) (for electronic climate control) uses the signal from the sun sensor to compensate for high sun intensity by decreasing the temperature of ventilation air, changing air distribution and increasing the speed of the blower fan.

The climate control module (CCM) (for electronic climate control and manual climate control) uses the signal from the evaporator temperature sensor to control the activation of the air conditioning (A/C) compressor. If the signal from the evaporator temperature sensor indicates an evaporator temperature below 6 °C, the compressor cannot be activated because of the risk of freezing.

To maintain a constant flow of air in the passenger compartment the climate control module (CCM) (for electronic climate control) uses the speed signal from the brake control module (BCM) to regulate the speed of the blower fan. Generally, as the speed of the car increases the speed of the blower fan decreases.

At higher speeds the flow of air into the fresh air damper is adjusted.