Automatic Climate Control (ACC) System
K 0Automatic Climate Control, ACC:
WIRING DIAGRAM
Automatic Climate Control: Component Location:
COMPONENT LOCATION VIEW
Automatic Climate Control: Component ID:
COMPONENT ID
16 Rheostat, lighting for controls, on dashboard between the steering wheel and driver's door.
22A Fuse board behind the cover flap in the glove box.
113 Relay, electrically heated rear window in the main fuse box behind the glove box.
198 Motor, air recirculation flap, on the evaporator casing.
199 Motor, ACC ventilation fan, in tan housing between the evaporator casing and heater housing.
210 EDU trip computer in the main instrument display panel.
216 ACC control module, in the centre of the dashboard.
217 ACC blended air temperature sensor, under the servo motor unit.
218 ACC interior temperature sensor, on the dashboard between the steering wheel and centre console.
219 Suction fan, ACC interior temperature sensor, on the dashboard between the steering wheel and centre console.
220 Speed control, ventilation fan, in the evaporating casing where it joins the fan housing.
221 Motor, ACC air distribution damper, on the servo motor unit behind the glove box.
222 Motor, ACC temperature valve, on the servo motor unit behind the glove box.
223 ACC solar sensor, on the top of the dashboard in the middle.
230 Distribution terminal (+30 circuit) in main fuse box behind the glove box.
231 Distribution terminal (+54 circuit) in main fuse box behind the glove box.
247 Motor, door fan, in the left-hand rear door.
248 Motor, door fan, in the right-hand rear door.
286 Outside temperature sensor, EDU/SCC, to the left behind the front spoiler.
348 Data link connector, under the right-hand seat (green).
(10-9)
2-Pin Connectors
H2-7 Adjacent to ventilation fan motor 199.
H2-29 In the right-hand rear door beside the fan motor.
H2-37 In the left-hand rear door beside the fan motor.
10-Pin Connectors
H10-4 Behind the glove box on the ACC servo motor unit.
H10-22 In right-hand B pillar.
H10-24 In left-hand B pillar.
H10-25 Behind the left-hand headlamp.
Grounding Points
G2 Grounding point, battery tray, on the left-hand wheel housing.
G5 Grounding point, rear seat, under the left-hand part of the seat.
G8 Grounding point, dashboard, by the left-hand front loudspeaker socket.
G24 Grounding point, right-hand front seat member.
GENERAL
Some cars are equipped with an Automatic Climate Control (AGO) system. The heating and ventilation system (including A/C) is then controlled automatically so that the desired temperature in the cabin is maintained at all times, regardless of the outside temperature. Air Conditioning (A/C) with a recirculation mode is always included in the ACC system.
The climate control unit has the following functions:
^ Automatic temperature control, including automatic control of recirculation.
^ Rear door fans.
^ Electrically heated rear window.
^ 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.
By pressing one of the buttons on the right of the unit, the particular function is manually switched on. If the button is pressed again, the function returns to the programmed mode.
Light-emitting diodes show which parts of the ventilation system are active, irrespective of whether the system is on automatic or under manual control.
To enable the system to achieve the required temperature in the cabin, data is required from a number of sensors, actuator motors, etc.
DESCRIPTION OF OPERATION
The climate control unit obtains data from both the control panel and the following sensors:
Cabin Temperature Sensor 218
Interior temperature sensor 218 is an NTC resistor which senses the temperature of the cabin air. The sensor has an integrated suction fan, 219, which gives an even air flow around the sensor. The sensor is connected via pins 15 and 33 while the suction fan is supplied with 12 V via pin 16.
Blended Air Temperature Sensor 217
The blended air temperature sensor is an NTC resistor which senses the temperature immediately after the air-mixing damper. The sensor is connected via pins 14 and 32.
Solar Sensor 223
The solar sensor consists of five solar cells arranged in a cube under the black cover. Pulses are sent to the solar sensor from ACC pin 5. Digital pulses are sent to ACC control module pin 6 via an amplifier stage.
Outside Temperature.
The outside temperature is obtained in the form of digital pulses from EDU trip computer 210 on pin 18 of the ACC control module.
Power Supply
Climate control unit 216 is supplied with current via fuses 17 and 1.
The unit always receives current
directly from the battery via fuse 17. This is the main supply for the system.
When the ignition switch is in the Drive position, the unit is also supplied with current via fuse 1. At the same time, suction fan 219 for interior temperature sensor 218 starts.
Ventilation fan 199 is supplied with current via fuse 6.
Pin 31 of the unit is connected to instrument lighting rheostat 16.
Climate Control Unit 216
The unit controls the following functions/units:
^ Ventilation fan 199 via speed control 220. Control of the speed is stepless. Control module pin 17 supplies the speed control with 12 V. A speed control voltage of 0-5 V is supplied via pin 20 where 0 V = fan stationary and 5 V = full speed.
^ Stepping motor -222 for the air-mixing damper which controls the flow of air, directing it through the heat exchanger or bypassing it. The motor is connected to pins 27, 28, 30 and 29.
^ Stepping motor 221 for the air-mixing damper which controls the air flowing through the defroster and/or ventilation outlet. The motor is connected to pins 23, 24, 26 and 25.
^ Servo motor 198 for the air recirculation flap. When the flap is closed, air is taken from outside and when it is open (air recirculation position), air is taken from the cabin. The motor is connected to pins 2 and 21 on the unit.
^ Electrically heated rear window 115 and heating element 207 in the door mirrors, which are controlled via relay 113. The relay is connected to pin 39. Connections to the relay are shown in detail in the Electrically Heated Rear Window.
^ Rear door fans 247 and 248 are connected to pins 9 and 10 respectively.
IMPORTANT: The cooling fin on the speed control is live (+12 V) when the ignition is on. If the cooling fin is grounded, the speed control will be rendered unserviceable.
FAULT DIAGNOSIS HINTS
When taking readings and during fault diagnosis, the connector must be removed. All readings must be taken on the connector and not on the climate control unit. With the exception of changing bulbs, the unit must not be tampered with.
Self-diagnostics
There is a special self-test program in the climate control unit's microprocessor.
The program regularly checks certain functions during driving, and an emergency program is activated if there is a fault in any of the sensors.
Faults detected by the self-test program are stored as diagnostic trouble codes in the memory of the microprocessor. Diagnostic trouble codes are read using the ISAT scan tool.
Calibration
The flap actuator motors must be calibrated at the following times:
^ After changing the control panel.
^ After changing the flap motors.
^ If the battery has been removed within 30 seconds of the ignition being switched off.
^ If the battery has been discharged or if battery positive voltage has been higher than 15 V.
Calibration is carried out either by simultaneously pressing the AUTO and <=> buttons or by means of the ISAT scan tool.
A self-test is carried out in conjunction with calibration. The total time for calibration and self-test is 22-50 seconds. The number of faults (0-5), if any, is shown in the display during the first 35 seconds.
Other Fault Diagnosis
1. Check that the relevant fuses are intact and supplied with current.
2. Check the interior temperature sensor suction fan by allowing a thin piece of paper to be sucked onto the intake.
3. Check the climate control unit connectors. Clean by unplugging and plugging them in again.
4. Check the connectors, wiring harness and ground connections.
For checking A/C compressors and radiator fans.
Resistances, blended air temperature sensor
Minimum Maximum
(Kohm) (Kohm)
+/-0°C 25.5 30.5
+ 10°C 16.6 19.6
+ 20°C 11.2 13.0
+ 30°C 7.7 8.8
+ 10°C 5.4 6.1
Interior temperature sensor
Minimum Maximum
(Kohm) (Kohm)
+/- 0°C 30.0 34.8
+ 10°C 18.5 21.1
+ 20°C 11.7 13.1
+ 25°C 9.5 10.5
+ 30°C 7.6 8.5
+ 40°C 4.9 5.6