Fault Code Guide

and the actuator still does not operate properly,
check for mechanical problems with the actuator. To
quickly check for normal operation, feel for air flowing
from the correct outlet in each air selection setting.
Air Distribution Door Actuator Circuit Tests
Test Conditions Test Point
Good
Result
What to Do if Test Fails
actuator motor
drive circuit
key on, engine off
air distribution door actuator
connector removed
fan (blower) speed on low
change the air selection setting
while observing the digital
multimeter (DMM)
Measure across pins 5 and 6
of the air distribution door
actuator connector.
9V+ for
about 1
second
*
Check wiring between control
head and air distribution door
actuator.
If wiring is okay, replace the
control head.
actuator
position sensor
reference
voltage circuit
key on, engine off
air distribution door actuator
connector removed
Measure between pin 10 of
the air distribution door
actuator connector and the
battery negative post.
5V
actuator
position sensor
reference
ground circuit
key on, engine off
air distribution door actuator
connector removed
Measure between pin 8 of
the air distribution door
actuator connector and the
battery positive post.
12V
*
actuator
position sensor
feedback signal
circuit
key on, engine off
all connectors connected
Backprobe pins B10 and B5
at control head connector.
0V (far
right) to
5V (far
left)
Check wiring between control
head and air distribution door
actuator.
†
If wiring is okay, replace the
actuator.
†
*
The voltage should be approximately the same as the battery voltage.
†
It is assumed that reference voltage and ground circuits are functioning.
Table 4, Air Distribution Door Actuator Circuit Tests
Recirculation Door Actuator
Circuit Tests
The recirculation door actuator controls the source of
the air, fresh or recirculated, that is routed through
the HVAC ducts in the cab. The recirculation door
actuator is controlled by the recirculation button on
the control head (climate control panel).
Vehicles built from May 2, 2003, have partial recircu-
lation. For information on this feature, see Sub-
ject 050.
The control rules for the recirculation mode are as
follows:
• The recirculation mode is not available in the
defrost settings.
• The default at power up is fresh air unless the
fan switch is in the off position. When the fan
switch is in the off position, the recirculation
mode is the default mode, but the LED is not
illuminated.
• When the recirculation mode is enabled, it will
remain on until one of the following occurs:
– the air selection switch is moved to a
defrost mode;
– the recirculation button is pressed;
– the ignition is cycled;
– 20 minutes have passed and the recircu-
lation timer has expired.
NOTE: On vehicles built prior to May 2, 2003,
the recirculation mode is canceled until the re-
circulation button is pressed again. On vehicles
built from May 2, 2003, the system enters partial
recirculation mode for five minutes, then re-
Cab Heater and Air Conditioner, Valeo 83.00
Troubleshooting
Business Class M2 Workshop Manual, Supplement 13, March 2008300/10