Service Manual

5-40 627333-A
HVAC Testing and Adjusting
Checking Actuator for Water Valve
Use the following to verify water valve actuator
operation:
1. Verify engine coolant system is full of coolant.
2. Turn switch to Head-Foot position.
3. Enter active troubleshooting, refer to Entering Active
Troubleshooting for instructions about active
troubleshooting.
4. CAB is first code displayed, continue to sensor
being verified. HEAT for check water valve actuator
will be displayed.
5. Engine coolant must be near operating temperature.
6. Set temperature control to maximum heat, display
should increase to 100. When a high number is
displayed, heated air should be felt from vents.
7. Set temperature control to maximum cooling.
Display should decrease to zero and air should
become cooler.
8. If displayed number does not change in steps 6 and
7 or if number does not reach 0 or 100, check the
following:
• Inspect wire connections for water valve
actuator.
• Check for damage on wire harness.
9. Replace water valve and check for normal
operation.
NOTE: If debris is found in the coolant system, flush
coolant system and determine source of debris.
10. If the problem continues, replace control module.
Checking Blower Fan
Verifying operation of blower fan:
NOTE: Problems with blower fan are normally obvious,
however, checking the output control of the
control module to blower motor may be
necessary.
1. Enter active troubleshooting, refer to Entering Active
Troubleshooting for instructions about active
troubleshooting.
2. CAB is first code displayed, continue to sensor
being verified. FAN will be displayed, check signal
being sent to fan from control module.
3. Display will show pulse width modulation sent to
blower motor. Value will range from 27-100. Vary
blower fan speed and verify pulse width modulation
changes.
NOTE: In AUTO mode, fan speed may not reach lowest
possible speed due to logic of control module.
4. If speed does not change, replace control panel.
Checking Mode Door Actuator
Use the following to verify mode door actuator operation:
1. Enter active troubleshooting, refer to Entering Active
Troubleshooting for instructions about active
troubleshooting.
2. CAB is first code displayed, continue to sensor
being verified. DOOR will be displayed, check signal
being sent to actuator from control module.
3. Value displayed will show current position of
actuator, from 0-100.
NOTE: Extremes of these values are not normally
reached as door stops prevent extreme
movements of actuator.
4. Use rotary switch to change position of actuator and
verify displayed value changes.
5. If displayed value does not change, inspect
following items:
• Wire connections.
• Check for wiring harness damage.
6. Replace actuator and check for normal operation.
7. If problem continues, replace control panel and
check for normal operation
8. If problem continues, replace control module and
check for normal operation.