Emerson Liebert DS Precision Cooling System 28-105kW User Manual

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. Find the restricted airflow switch in the cooling unit (see Figure 7; the illustration shows the 

switch location in both the Liebert CW and Liebert DS units).

3. Turn On the Liebert DS or Liebert CW—the cooling unit must be running for the switch to be 

adjusted.

4. Turn the restricted airflow switch alarm setpoint knob clockwise until it trips. The cooling unit 

will also alarm.

5. Turn the setpoint knob counterclockwise:

a. half a turn for standard cooling units (about 75% airflow)
b. one full turn for cooling units equipped with a variable frequency drive (about 50% airflow)
c. or to the desired setpoint.

E

FRONT VIEW

120" Frame, Chilled Water
Restricted Airflow
Switch Location

Liebert DS + CW026-CW084
Restricted Airflow
Switch Location

P13 Factory-
Connected

Secure Supply Air Thermistor
In Airflow (120" Frame, Chilled
Water Location)

Secure Supply Air Thermistor
in Airflow (Liebert DS and
CW026-CW084 unit location)

P13 Factory-
Connected

DETAIL E

Restricted Airflow Switch

DPN001449
Pg. 05, Rev. 02

Restricted Airflow
Switch Alarm
Setpoint Knob

ADJUSTMENT INSTRUCTIONS:
1. Unit must be running.
2. Turn the adjustment knob clockwise
    until you hear it trip. Unit will also alarm.
3. Turn the adjustment knob back
    counterclockwise:
  - 1/2 turn for standard units
  - 1 turn for units with VFD
  - or to desired setpoint

Uncoil and
Extend Cable
Through Holes
Provided in
Bottom of Unit

Uncoil and
Extend Cable
Through Holes
Provided in
Bottom of Unit

Both po

ssible l

ow-volt

age

compar

tments 

shown.

Determ

ine whi

ch app

lies.