Fault Code Guide

Temperature Blend Door Actuator Circuit Tests
Test Conditions Test Point
Good
Result
What to Do if Test Fails
actuator motor
drive circuit
key on, engine off
temperature blend door actuator
connector removed
fan (blower) switch on low
change temperature setting
while observing the digital
multimeter (DMM)
Measure across pins 5 and 6
of the temperature blend
door actuator connector.
9V+ for
about 1
second
*
Check wiring between control
head and temperature blend
door actuator.
If wiring is okay, replace the
control head.
actuator
position sensor
reference
voltage circuit
key on, engine off
temperature blend door actuator
connector removed
Measure between pin 7 of
the temperature blend door
actuator connector and the
battery negative post.
5V
actuator
position sensor
reference
ground circuit
key on, engine off
temperature blend door actuator
connector removed
Measure between pin 8 of
the temperature blend door
actuator connector and the
battery positive post.
12V
*
actuator
position sensor
feedback signal
circuit
key on, engine off
all connectors connected
Backprobe pins B11 and B5
at control head connector.
0.50V
(full hot)
to
4.00V
(full
cold)
†
Check wiring between control
head and temperature blend
door actuator.
‡
If wiring is okay, replace the
actuator.
‡
*
The voltage should be approximately the same as the battery voltage.
†
Values are approximate.
‡
It is assumed that reference voltage and ground circuits are functioning.
Table 3, Temperature Blend Door Actuator Circuit Tests
Air Distribution Door Actuator
Circuit Tests
The air distribution (mode) door actuator controls the
direction the air is routed through the HVAC ducts in
the cab. The air distribution door actuator is con-
trolled by the air selection switch on the control head
(climate control panel). The control head senses the
air distribution door position by reading the feedback
voltage from the actuator position sensor. The feed-
back voltage will be less than the 5V reference volt-
age sent by the control head to the sensor.
The target position is based on the air selection
switch setting and internal control head algorithms.
The desired position is considered reached when
one of the following conditions is true, although this
does not necessarily mean that the position actually
corresponds to the desired air selection setting (for
example, if the actuator movement is limited due to
an obstruction).
• The actuator feedback position has been
reached.
• The actuator is stalled for more than 1 second;
the actuator feedback position does not
change for more than 1 second.
• The target position corresponds to an end stop
and an additional 1 second extra drive in the
same direction (to guarantee sealing) has been
performed.
The air distribution door should move from one ex-
treme position to the other when turning the air se-
lection switch from the far left to the far right or from
the far right to the far left.
Follow the tests in Table 4 in the sequence pre-
sented. The directions under the column "What to Do
if Test Fails" are sometimes dependent on good re-
sults from previous tests. If any of the tests fail, stop
and perform the specified repair or check. If the air
distribution door actuator passes the tests in Table 4
Cab Heater and Air Conditioner, Valeo 83.00
Troubleshooting
Business Class M2 Workshop Manual, Supplement 13, March 2008 300/9