Emerson Liebert MC Microchannel Outdoor Condenser 28 - 220kW Manuel D’Utilisation

Liebert MC condensers are charge-sensitive and require accurate calculation of the system charge to 

avoid overcharging. To avoid overcharge, additional guidelines are recommended to ensure trouble 

free operation.

• When charging system in an outdoor ambient below 50°F (10°C), recheck the subcooling against 

Table 13 when the ambient is above 60°F (15.6°C)

• The indoor space should be maintained at 70 to 80°F (21 to 26.7°C) return air before final charge 

adjustments are made.

• Charging unit at greater than 80°F (26.7°C) return air may result in the unit being overcharged.
• Charge by subcooling measurement at the indoor unit. See Table 13 for target subcooling 

temperatures.

• Pressure and temperature measuring instruments should be capable of measuring to ±10 psig 

(103.4kPa) and ± 2°F (1.1°C) for best subcooling measurement.

1. Check indoor nameplate for refrigerant type to be used. Unit control configurations differ 

depending on refrigerant type.

2. Refrigerant charging requires unit operation. Refer to the indoor unit’s user manual for details 

regarding indoor unit operation and 6.0 - Checklist for Completed Installation for the Liebert 

MC condenser operation.

3. Calculate the amount of charge for the system. Refer to the indoor unit user manual, and 

condenser and refrigerant line charge data in Tables 10 and 12. 

4. Accurately weigh in as much of the system charge as possible before starting the unit. Do not 

exceed the calculated charge by more than 0.5 lb (.37kg).

Risk of improper refrigerant charging. Can cause equipment damage.
Refrigerant R-407C and R-410A are blended refrigerants and must be introduced and charged 

from the cylinder only as a liquid.
When adding liquid refrigerant to an operating system, it may be necessary to add the 

refrigerant through the compressor suction service valve. Care must be exercised to avoid 

damage to the compressor. Emerson recommends connecting a sight glass between the 

charging hose and the compressor suction service valve. This will permit adjustment of the 

cylinder hand valve so that liquid can leave the cylinder while allowing vapor to enter the 

compressor.

Risk of refrigerant overcharge. Can cause equipment damage.
Do not use the sight glass as an indicator when charging Liebert MC condenser systems.

5. Turn On the Liebert MC disconnect switch.
6. Turn on the indoor unit disconnect switch. Operate the unit for 30 minutes using the charging 

function of the indoor unit control for each circuit of the system. The charging function is in the 

diagnostic section of the Liebert iCOM

®

 control (see Liebert iCOM user manual, SL-18835). The 

charging function operates the compressor(s) at full capacity and energizes the liquid line 

solenoid valve(s). The reheat and humidifier are disabled. Manual operation of the indoor fans 

from the diagnostic menu of the Liebert iCOM is required. A minimum 20psig (138kPa) must be 

established and maintained for the compressor to operate. The charging function can be reset as 

many times as required to complete unit charging.

7. Attach pressure and temperature instruments to the liquid line of the indoor unit. Measure the 

initial subcooling and continue to add charge until recommended subcooling for the current 

outdoor ambient temperature is reached. See Table 13. The outdoor ambient can be read from 

the Liebert MC condenser control menu ID F02.