
Climate Control Systems 
SECTION  CON TENTS 
Subsection Title SRO Page 
14.1 ............. System  Description ................................................................... 1 
14.2 ............. Component Descriptions .............................................................. 3 
14.2.1 ............ Control  Panel ........................................................................\
 3 
14.2.2. ........... Control Panel Inputs / Outputs ......................................................... 3 
14.2.3. ........... Solar Sensor ........................................................................\
. 4 
14.2.4. ........... Engine  Speed Signal .................................................................. 4 
14.2.5 ............ Ambient Temperaturesensor ........................................................... 4 
14.2.6 ............ Vehicle  Speed Signal ................................................................. 4 
14.2.7. 
........... Evaporator  Temperature  Sensor ......................................................... 4 
14.2.8. ........... Heater Matrix  Temperature  Sensor ...................................................... 5 
14.2.9. 
........... Coolant  Temperature Signal ............................................................ 5 
14.2.10 
.......... Compressor ONSignal ................................................................ 5 
14.2.11 ........... Motorized ln-car Aspirator ............................................................ 5 
14.2.12 .......... CompressorLockSignal ............................................................... 5 
14.2.13 
.......... Refrigerant  Pressure Switch ............................................................ 5 
14.2.14 
.......... Water  Valve ........................................................................\
. 5 
14.2.15 .......... Water Pump ........................................................................\
. 5 
14.2.16 
.......... Servo  Motor  Control .................................................................. 6 
14.2.17 .......... Blower  Motor  Control ................................................................ 6 
14.2.18 .......... Differential Control ................................................................... 6 
14.2.19 
.......... Heated  Rear Window, Door Mirrors  and Front Screen ...................................... 6 
14.3 ............. Climate Control  Module Connections ................................................... 7 
14.4 ............. Climate Control  System Test .......................................................... 10 
14.4.1 
............ Fault Code  Extraction and Deletion  Procedure ........................................... 10 
14.5 
............. Fault  Codes ........................................................................\
 11 
14.6 ............. Actuator  Check ..................................................................... 12 
14.7 
............. Diagnostic  Tests .................................................................... 13 
14.7.1 
............ Fault Code 11 ...................................................................... 13 
14.7.2. 
........... Fault Code  12 ...................................................................... 14 
14.7.3 
............ Fault Code  13 ...................................................................... 15 
14.7.4. 
........... Fault Code  14 ...................................................................... 16 
14.7.5 
............ Fault Code  15 ...................................................................... 16 
14.7.6 
............ Fault  Code21 ...................................................................... 17 
14.7.7 ............ FaultCode22 ...................................................................... 17 
14.7.8 ............ Fault Code23 ...................................................................... 18 
14.7.9. ........... Fault Code  24 ...................................................................... 18 
X300 EDM i Issue 1 August 1994  

Climate Control Systems 
14.2.16  Servo Motor  Control 
The system incorporates  several servo motors  which direct the flow of  air through the  air conditioning  system. The 
motors  are driven  by A / CCM signals  in either a clockwise or anti-clockwise direction. 
Servo  motor  position  is monitored  via 
a feedback potentiometer situated  within the motor housing. 
The  system  servos comprise: 
o RH and LH Air  intake servos (Fresh / Recirc.). 
0 Centre  vent servo. 
o Defrost (screen  vent) servo. 
0 Footservo. 
0 Cool air by-pass  servo. 
14.2.17  Blower Motor Control 
The A/ CCM controls  two blower  motors,  delivering  airflow 
to  the  evaporator / heater unit, at variable  fan speeds.  The 
blower motors  are regulated  by power transistor  modules 
which  provide linear  variation of blower  speed; the blower 
speed 
is increased  or reduced  progressively in response  to 
vehicle  speed, minimising  the ram  effect  of forward  motion. 
The  blower motors  are inhibited when  engine coolant tem
- perature is below 30°C and  heating  is requested. 
14.2.18  Differential Control 
The differential  control is mounted  on the  facia  centre  vent. It is used  to control  the temperature  difference between the 
upper and lower  outlets.  Fig. 
1 Servo 
Motor 
14.2.19  Heated Rear Window,  Door Mirrors  and Front  Screen 
The Heated  Rear Window (HRW) function  can only  be activated  with the ignition  on and  the engine running.  Operation of the HRW  switch  operates  the status  condition  LED on the  control  panel and switches  on the HRWfor approximately 21 minutes.  Selection  of the  HRW  also operates  the door mirror heaters  for approximately 11 minutes.  The operation 
can  be cancelled  by switch  re-selection  or ignition off. System off does  not cancel  the HRW  operation. 
The Heated Front Screen 
(HFS) function  can only  be activated  with the ignition  on and  the engine  running,  and either 
‘defrost’  mode selected  or HFS  selected.  Each half, left and right hand  split, switches  on for approx. 6.5 minutes.  The 
operation  can be cancelled  by switch  re-selection  or ignition off. System off does  not cancel  the HFS  operation. 
0 
0 
Issue 1 August 1994 6 X300 EDM