Ingersoll-Rand Thermo King CRR DF MPC2000, Maintenance Manual

Page: 116 / 165

Refrigeration Maintenance and Service Operations
115
Checking the R-23 Refrigerant Charge
The R-23 refrigerant charge should be checked with the container empty, the unit OFF and all
refrigeration system components above -5 C (23 F). The R-134a compressor must not have been operated
within the past 30 minutes and there must not be frost on the plate-type R-134a / R-23 heat exchanger
tubing.
Observe both the suction and discharge pressures. With the unit OFF, the suction and discharge readings
should be equal. The R-23 refrigerant pressure in a fully charged system with the unit OFF will vary with
the ambient temperature:
• Correct Refrigerant Charge: If the R-23 system pressure stabilizes between 1500 and 2000 kPa, 15
and 20 bar, 220 and 290 psig, the unit will be fully functional. The R-23 refrigerant charge requires no
adjustment.
• Low Refrigerant Charge: If the R-23 system pressure stabilizes between 1000 and 1500 kPa, 10 and
15 bar, 145 and 220 psig, the unit cooling capacity will be reduced but the unit should be able to
maintain a -55 C to -60 C (-62 F to -76 F) load temperature. Additional R-23 should be added if
possible, but do NOT add by operating the unit.
• Over Charge of Refrigerant: If the R-23 system pressure stabilizes above 2000 kPa, 20 bar, 290 psig,
the R-23 system is overcharged and may cause the compressor to stop on high pressure cutout when
started to precool a warm container. Remove refrigerant until the system pressure stabilizes at 2000
kPa, 20 bar, 290 psig or below.
Ambient Temperature R-23 System Pressure
O C (32 F) 1600 kPa, 16 bar, 232 psig
20 C (68 F) 1700 kPa, 17 bar, 247 psig
38 C (100 F) 1800 kPa, 18 bar, 261 psig
1. The bottom sight glass ball will rarely float on a fully charged system during normal
operation.
• Check the refrigerant charge based on the R-23 system pressure with the container
empty, the unit OFF and all refrigeration system components above
NOTE: Use the lower sight glass to check or add refrigerant only on a operating unit
that is unable to maintain a -55 C to -65 C (-62 F to -76 F) low temperature.
Figure 38: R-23 Refrigeration System Receiver Tank