Automatic Climate Control (ACC) System
�0Automatic Climate Control, ACC:
WIRING DIAGRAM
Automatic Climate Control, ACC - Component Location:
COMPONENT LOCATIONS
16 Instrument lighting rheostat, in switch assembly between the steering wheel and driver's door.
20 Ignition switch on centre console between the front seats.
22A Main fuse board in the dashboard.
113 Relay, electrically heated rear window, on main relay board in dashboard.
115 Electrically heated rear window
198 Motor, recirculation flap, on the evaporator housing behind the glove box.
199 Motor, ventilation fan, in the centre between the bulkhead partitions.
216 ACC control module in centre of dashboard.
217 Blended air temperature sensor on the heater housing's duct leading to the right-hand front floor vent.
218 Cabin temperature sensor in switch as- 219 assembly on centre console.
220 Ventilation fan speed control on right- hand side of evaporator.
221 Motor, air blending flap, on heating and ventilation unit behind the centre console.
222 Motor, air blending flap, on end of heating and ventilation unit behind the centre console side panel on the passenger side.
223 Solar sensor, on the top of the dashboard in the centre.
445 Data link connector under the dash board adjacent to the steering column.
(H16-1)
500 ICE control module
LHD:above main relay board in dashboard
RHD:behind main relay board in dashboard
540 Main instrument display panel on the dashboard.
541 SID unit in centre of dashboard.
8-pin connector
H8-1 Adjacent to the fan speed control.
10-pin connector
H10-5 On heater housing.
Grounding Points
G3 Grounding point, luggage compartment, below left-hand rear light cluster.
G33P Grounding point, control module bracket (Power) below the right-hand A pillar.
G34P Grounding point, control module bracket (Power) below the right-hand A pillar.
DESCRIPTION OF OPERATION
Certain cars are equipped with automatic Climate Control (ACC). The heating and ventilation system is then controlled automatically so that the desired cabin temperature will be maintained regardless of the ambient temperature. The system always includes air conditioning (A/C) with recirculation.
A brief description of the ACC system is given below.
The ACC control module incorporates the following functions:
^ Automatic temperature control, including automatic control of recirculation.
^ Automatic control of air distribution.
^ Electrically heated rear window, including electrically heated door mirrors.
The A/C compressor is deactivated using the ECON button while the other functions are still controlled automatically.
The system can be switched OFF with the OFF button. Pressing any of the buttons ON the unit switches on the corresponding function manually. If the AUTO button is pressed again, the programmed operational mode will be resumed.
When the system is in automatic mode, only the preset temperature will normally be shown on the display. If the system automatically selects recirculation or the electrically heated rear window, this will also be indicated. To obtain a display of the fan or air distribution setting, it will be necessary to press the AUTO button once again. Manual selection of a function is always shown on the display.
Components Of The ACC System
To enable the system to maintain the desired climate in the cabin, it will need information from a number of sensors as well as motors for operating corresponding flaps, etc.
Operation of the system is described under the following headings:
^ Communicated sensor values
^ Own sensors and flap actuator motors
^ Power supply
^ ACC control module
Communication With Other Units
The ACC control module communicates with both the main instrument display panel and the side instrument display via pins 11 and 13. The SID supplies the unit with the following information:
^ Outside temperature.
^ Background lighting level and black panel.
^ "Motor off" time.
The main instrument display panel supplies the unit with the following information:
^ Coolant temperature.
^ Speed.
Own Sensors And Flap Actuator Motors
The ACC control module makes use of its own sensors as follows:
^ Blended air temperature sensor 217, of NTC type, senses the temperature in the duct leading to the right-hand front floor vent. The sensor is connected via pins 32 and 14.
^ Cabin temperature sensor 218, of NTC type, senses the temperature of the air in the cabin. The sensor is integrated with suction fan 219 which provides an even flow of air round the sensor. The sensor is connected to pins 15 and 33 while a positive power supply for the suction fan comes from pin 16. The suction fan is grounded via pin 1 of the fan control unit connector.
^ The solar sensor for measuring solar intensity consists of 1 solar cell located under the black cover. It is connected via pins 34 and 35.
Power Supply
ACC control module 216 is supplied with power via fuses 21 and 27.
The unit is always supplied with current directly from the battery via fuse 27. This is the main power supply for the ACC system.
When the ignition switch is in the Drive position, the unit is supplied with current via fuse 20. This input is used only for sensing this position.
The ventilation fan is supplied with current via fuse 3.
Pin 30 of the unit is connected to instrument lighting rheostat 9. This input controls only the background lighting of the pushbuttons.
ACC Control Module 216
The unit controls the following functions/units:
^ Ventilation fan 199 via fan speed control 220. The speed is continuously variable and the control is connected to pin 20. The voltage between the fan and the speed control is measured on pin 37.
^ Stepping motor 222 for the air blending flap, which controls the flow of air through or past the heat exchanger. The motor is connected to pins 8, 27, 28 and 29.
^ Stepping motor 221 for the air distribution flap, which controls the flow of air through the demister and/or cabin ventilation vents. The motor is connected to pins 23, 24, 25 and 26.
^ Servomotor 198 for the recirculation flap. When the flap is closed, air is taken from outside and when it is open (recirculation position), the air is taken from inside the cabin. The motor is connected to pins 2 and 21.
^ Electrically heated rear window 115 and electrically heated door mirrors 207, which are controlled via Integrated Central Electronics (ICE) 500. This in turn controls relay 133. Pin 39 emits a short pulse each time the electric heating elements are to be switched on or off. The relay coil voltage is measured on pin 31 to ascertain whether the relay has operated or released.
^ A/C compressor 170, which is turned on and off via the ICE. Only depressing the ECON button will affect pin 38. In the AUTO mode, the voltage is always lower than battery voltage and in the ECON mode it is close to 0 Volts. Normal cycling of the AC compressor does not take place via this output but via antifrost thermostat 171.
FAULTS DIAGNOSIS HINTS
In general, the Automatic Climate Control (ACC) system will be supplied with current when the ignition switch is in the Drive position. If a malfunction has occurred and no defective component can be found, check the wiring, connectors and ground connections. Light bulbs can be changed through holes in the rear panel.
Fault diagnosis is to be carried out using an Intelligent Saab Tester (ISAT)scan tool.
Calibration
The flap actuator motors must be calibrated on the following occasions:
^ After replacement of the ACC control module.
^ After replacement of the flap actuator motors for heating and air distribution.
^ If the battery has been disconnected, within 30 seconds of switching OFF the ignition.
Calibration is carried out either by pressing the AUTO and OFF buttons simultaneously or by means of an ISAT scan tool.