Liebert DS User Manual

1. Disconnect all power to the environmental control unit and check.
2. Remove all line voltage fuses except the main fan fuses and the control voltage fuses in the 

electric panel. (Use iCOM to activate loads).

3. Turn on power to the unit and check line voltage on main unit disconnect switch. Line voltage 

must be within 10% of nameplate voltage.

4. Turn ON the main unit disconnect switch and check secondary voltage at transformer T1. Voltage 

at T1 must be 24VAC ±2.5VAC (check at TB1-1 and TB1-5). T1 voltage must not exceed 28VAC. 

Change primary tap if necessary.

5. Push the ON button. Blower will start and On lamp will light. Check fan rotation if not correct 

make necessary changes to the line side of the unit disconnect with power Off. (The unit is 

6. Your unit will operate at the factory set configuration for all component operations the operator 

may set the values for temperature and humidity setpoints, the proportional band, the deadband. 

The User Menu may used to set the alarms and other control functions. Refer to iCOM User 

manual, SL-18835, for large or small display operation and settings.

7. Turn Off the unit by the On-Off button and then remove power from main unit disconnect and 

main breaker and check with a meter.

8. Replace all fuses you removed in Step 2.
9. Restore power to unit; turn ON the main unit disconnect switch, press the on button. 
10. Check and record the current draw on all line voltage components and match with serial tag.

11. Check for unusual noises and vibration. Note on warranty inspection form’s comments section.
12. Check all refrigerant and water lines for leaks. Note on warranty inspection form’s comments 

section.

13. Record all of the following on the warranty inspection form:

a. All component voltages and current draws
b. All air / water temperatures indoor and outdoor
c. All refrigerant and water / glycol pressures,
d. All levels of refrigerant and oil in sight glasses
e. Record refrigerant pressure switch settings and operating pressures
f. Record superheat and sub-cooling.

14. Test all control sequences and functions of your unit for proper operation. Use iCOM User Manual 

for guide to system control operations.

15. Complete the warranty inspection form with sign-off data.

Local Emerson sales offices and air product support contacts can be found on the Liebert Web site: 

 or call 1-800-LIEBERT for Air Product Support.

NOTE
Electric Reheat. See Warning on page 108. Activate for a minimum of five (5) minutes.

NOTE
Unit superheat cannot be adjusted but should be in the range of 10 to 20°F (-12 to -6°C).