freightliner MT45 2019, Service Manual

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2019 Amazon P80 Package Delivery Vehicle
TROUBLESHOOTING
SECTION A: AIRFLOW PROBLEMS
PROBLEM A-1
,
No air flow, blower does not operate
POSSIBLE CAUSE #1
-
Faulty Blower Motor
CORRECTIVE ACTION
-
With ignition turned ON, unplug the 2-pin connector at the blower mo-
tor. Check the orange wire for +12 volts and the white wire for a fully grounded circuit. If power is
present and the circuit grounded, remove the motor and wheel from the blower housing. Inspect
for any evidence of entrapped debris or a broken blower wheel that might have prevented rotation.
If no such evidence exists, replace the blower motor.
POSSIBLE CAUSE # 2
- Blown fuse due to short in wire harness.
CORRECTIVE ACTION
- Refer to the HVAC Wiring
Diagram and the Chassis
Manufacturer's wiring infor-
mation.
Trace the entire HVAC wiring
for an electrical short.
Replace or repair as required.
POSSIBLE CAUSE #3
-
Defective Blower Switch.
CORRECTIVE ACTION
-
Refer to the Blower Switch
Continuity Diagram
(Figure 1) and check the
blower switch for continuity
through the switch in all four
switch positions.
Replace the blower switch as
required.