Group 87 Climate Control, Fault Codes
Troubleshooting
MID 146 SID 9 Stepper Motor, Air Mix
Air mixture (ECC), heat control (MCC, BAS)
T8008643
T8008563
Component: A34 Climate Control Unit, E32 Climate
unit
General information
The stepper motor controls the amount of air which
is permitted to flow into the cab without passing the
heat exchanger. The stepper motor is located on the
left side on the climate control unit. The stepper motor
also controls the mechanical engine coolant valve and
therefore the coolant flow through the heat exchanger
(only MCC and BAS). The mechanical engine coolant
valve is located in the climate control unit.
Fault code
FMI 4
Abnormally low voltage or short-circuit to lower voltage
Conditions for fault code:
•
If the control unit detects a short-circuit to ground, the
control unit interprets this as an error and an fault code
is stored.
Possible cause:
•
Signal cable to air mixture stepper motor short circuited
to lower voltage
•
Signal cable to air mixture stepper motor short circuited
to ground
Reaction from the control unit:
•
Fault code is stored
•
Yellow lamp requested
Noticeable external symptoms:
•
Yellow lamp lights up
•
No control of air mixture / heat control
•
ECC- Impaired control of air mixture
•
MCC/BAS- Impaired heat control
Appropriate check:
•
See “MID 146 SID 9 Stepper Motor, Air Mix/Heat
Control, Check ” page 19
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