User manual

Operation
35 Liebert
®
iCOM
®
3.3.3 Adjust the Restricted Airflow Switch on the Liebert Air Economizer
™
The restricted airflow switch inside the cooling unit must be adjusted for the Liebert Air Economizer
to operate properly and efficiently. To adjust the switch:
1. Inspect all connections, restore power to operate the unit’s blower.
2. Go to the Service Menus, Diagnostic / Service Mode.
3. Enter the Service Menu password 5010.
4. Enable manual mode on line S313. The unit will shut Off.
5. Go to line S314 Motors and change the value displayed from No to Yes. This will allow the
evaporator fan to run with the outside air damper at minimum position.
6. Confirm the fan is running at minimum speed. This is shown on line S343 “Analog Out 3” of the
Diagnostics / Service Mode.
7. Confirm the outside air damper has moved to the minimum position by visually checking damper
position.
8. Find the restricted airflow switch in the cooling unit (Figure 32 shows the switch location in both
the Liebert CW
™
and Liebert DS
™
).
9. Turn the restricted airflow switch alarm setpoint knob clockwise until it trips. The cooling unit
will also alarm.
a. Place a voltmeter on Terminal 56 and on the chassis ground.
b. Turn the airflow sensor counterclockwise until the voltmeter indicates 0VAC.
c. Turn the airflow sensor adjustment screw clockwise until the voltmeter indicates 24VAC.
d. When the voltmeter shows 24VAC, turn the screw counterclockwise one full turn.
Once the airflow switch has been calibrated, go to the Service Menus, Diagnostics / Service Mode.
Using the Service Menus password 5010, disable manual mode on line S313.
The reduced airflow alarm is latched in the control for 90 minutes after calibration. Acknowledge this
alarm and allow it to clear by pressing the horn button on the control once. The alarm may also be
cleared by shutting Off power to the Liebert iCOM and cycling power to the cooling unit. The unit will
now resume normal operation.