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To charge, connect the pressure gauge manifold set to the high and low ports near the
compressor. Connect the charging line to the refrigerant tank and set for liquid feed. Open the
refrigerant tank valve and purge the line.
Use a “liquid charging adapter” to break the vacuum with 90 PSIG (621 kPa) of liquid
refrigerant so liquid refrigerant doesn’t enter the compressor through the open compressor
suction and discharge Rotolock service valves.
Before starting the system, charge the receiver with liquid refrigerant through the liquid line
leaving the receiver. Weigh in the refrigerant until the proper amount of refrigerant is added
that is required by the receiver in the system (see Table 4 Refrigerant Receiver Charging
Chart), or enough refrigerant to provide a liquid seal in the receiver. Receiver storage
capacities are based on the liquid occupying no more than 90% of the internal volume when
the temperature of the refrigerant is 90°F (32°C) per ASHRAE Standard 15-94.
Use 2 lbs. per nominal ton and using a “liquid charging adapter” add the calculated system
charge at the condenser through the liquid line and discharge line with liquid refrigerant. A
“liquid charging adapter” is needed so liquid refrigerant doesn’t enter the compressor.
At this point the receiver(s) are pre-charged.
Charge Fixed Speed Compressor
While charging, if the receiver (head) pressure is below the value shown in the table below for
the refrigerant type used, block part of the condenser coil surface or turn OFF the fans until
the pressure rises to the value shown in the table below or higher, while observing the
receiver sight glass. During extremely cold weather, all the condenser fans may have to be de-
energized to maintain head pressure. Once you reach the pressure value shown in the
Table 5
Discharge Head Pressure
below, enable the condenser fans and continue to charge each
circuit until it reaches the value shown in the Table 5 Discharge Head Pressure below again.
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