Service Manual

627333-A 5-15
HVAC
Troubleshooting
To display diagnostics, depress key three times. Digital
display shows any active fault codes. Repeatedly
pressing key scrolls through active codes. Each code
displayed should be addressed until No Faults code E00
is displayed.
Fault Codes
For all fault codes is the possible solution check the
wiring and connectors.
No Display
• Press control panel on key.
• Make sure display illuminates.
• Verify control panel is plugged into wire harness.
• Check if wire harness is wired into vehicle properly.
No Fan
• Turn up fan with fan up key.
• Make sure fan is plugged into wire harness.
• Verify circuit breakers or fuses are intact.
• If all other functions work properly, replace electronic
control unit (ECU).
No Heat
• Turn up heat with temperature up key. Use the
advanced diagnostics to verify that the water valve
is commanded open.
• Inspect and verify all wiring connections.
• Verify that any coolant shut off valves on the engine
are open.
• Verify that warn coolant is flowing into the heater
core by testing the heater hoses.
• Inspect and replace the electronic water valve if
necessary.
• Inspect and replace ECU if necessary.
No Cooling
• Turn down heat with temperature down key and
enable defrost mode. Use the advanced diagnostics
to verify that the A/C clutch is requested ON.
• Verify that the system is fully charged with
refrigerant.
• Verify correct voltage is present at clutch relay on
wire harness.
• Inspect and verify all wiring connections.
• Inspect and replace clutch relay if necessary.
• Inspect and replace refrigerant high pressure and/or
low pressure cut out switches if necessary.
• Inspect compressor and clutch assembly and clutch
assembly and replace clutch if necessary.
The system is not controlling the cab temperature
properly.
• Inspect the Cab Air Temperature sensor.
• Verify that the recirculation vent inlet not obstructed.
• Inspect and replace recirculation vent air filter if
necessary.
• Change the setpoint temperature in small
increments.
• Verify that the water valve is working properly (see
No Heat).
• Verify that the compressor clutch is working properly
(see No Cooling).
The evaporator core is icing up and restricting
airflow.
• Inspect the Evaporator Core Probe.
• Verify that the probe is making good contact with the
evaporator fins and is not loosely inserted.
• Reposition the probe and check the core
temperature during operation using the advanced
diagnostics.
• Replace the evaporator core if necessary.
System is putting out cool air when heat is
needed.
• Reposition cab temperature sensor as required.
• Verify compressor clutch is working properly (see
No Heat).
System is putting out hot air when cooling is
needed.
• Reposition cab temperature sensor as required.
• Verify compressor clutch is working properly (See
No Cooling).
Cause Display Reads
No Faults Detected EO
Cab Sensor Shorted E1
Cab Sensor Open E2
Evap Probe Shorted E3
Evap Probe Open E4
Water Valve Shorted E9
Water Valve Open E10
No Communications w/ ECU E17