2. Refer to Refrigerant Charge Requirements on page14, and calculate the amount of charge for
the system including the evaporator, condensing unit, and interconnecting piping.
3. Accurately weigh-in as much of the system charge as possible before re-installing the coil on
the liquid-line solenoid valve and starting the unit.
Field Charge Verification
The unit receiver includes an integral sight glass to assist with charge verification in the field.
To verify the refrigerant charge:
1. To keep the unit operating, use the Service menu at the iCOMtouchscreen control:
• Touch the Service icon to display the service menu, then touch Diagnostics/Service.
• Touch the Compressor Circuit options, and select 2 (charge mode) in the Compressor
Mode field.
The compressor runs at 100% for 30 minutes in charge mode.
2. At design ambient temperature between 95°F and 105°F (35°C and 41°C), the charge level
should be in the middle of the sight glass.
• If the charge level is below the sight glass, an under-charge condition is likely.
• If the charge level is above the sight glass, and you observe a higher than normal
discharge pressure, an over-charge condition is likely. However, before removing charge,
make sure that there are no other possible causes of high discharge pressure such as a
dirty coil or restricted air flow.
3. Below design ambient temperatures, refrigerant backs-up into the condenser coil and the
charge level drops below the sight glass. At lower ambient temperatures, block the condenser
coil to maintain 418psig (2882kPa) discharge pressure to ensure that the head-pressure
control valve is closed. The charge level should be in the middle of the sight glass with the
valve closed.
• If the charge level is below the sight glass, an under-charge condition is likely.
• If the charge level is above the sight glass, an over-charge condition is likely.
NOTE: In systems with two condenser coils and two receivers, block-off coils proportionally. If one coil
is restricted significantly more than the other, liquid can remain in the restricted coil causing lower
levels in the receiver. The liquid level should be in the middle of the sight glass in both receivers. There
may be some variation in charge level between the receivers. When adding charge, use the receiver
showing a lower charge level and use that sight glass to determine the charge level.
4. If no level is visible in the sight glass, add charge until the level is in the middle of the glass.
Check the discharge pressure and adjust the coil restrictions to maintain418psig (2882kPa).
5. After conditions have stabilized, restrict the coil, if required, to maintain 418 psig (2882kPa)
discharge pressure and verify that the charge level is in the middle of the sight glass.
Vertiv | Liebert® PFD™ Installer/User Guide
18
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