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Maintenance
18
9. Connect a vacuum pump to both the high and low sides of the system through properly sized
connections. Evacuate the system twice to 1500 microns, and the third time to 500 microns. Break
the vacuum each time with dry nitrogen to 2 PSIG (13.8 kPa).
10. Charge the system with refrigerant. Refer to unit serial tag for refrigerant charge amount.
11. Apply power and operate system. Check for proper operation. Suction and discharge pressures
will vary with load conditions and coil efficiency. The low pressure switch will shut the
compressor down if the suction pressure falls below the cutout setting. Conversely, the high
pressure switch will shut down the compressor if the discharge pressure exceeds the cutout
setting. High suction pressure reduces the ability of the refrigerant to cool compressor
components and can result in compressor damage. Refer to Table 4.
NOTE
High side gauge port is a liquid line connection. Proper procedures should be followed
when installing and removing gauges. A 6-foot (1.8 m) hose can hold up to 3 oz (0.1 l) of
refrigerant. Be sure to purge high side to low prior to removal.
Table 4
Pressure information
Design
Pressures
psig (kPA)
Minimum
psig (kPa)
R-22
Maximum
psig (kPa)
R-22
Suction 35 (241) 90 (620)
Liquid (Approx.) PSIG (kPa)
95°F (35°C) Ambient 250-290 (1723-2000)
Maximum 360-380 (2480-2618)
High Pressure Cutout 400 (2756)
Based on indoor conditions of 80°F (26.7°C), 50% RH, with clean filter(s).