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RTAC-SVX01F-EN 155
Maintenance Procedures
Refrigerant and Oil Charge Management
Proper oil and refrigerant charge is essential for proper unit operation, unit perfor-
mance, and environmental protection. Only trained and licensed service personnal
should service the chiller.
Some symptoms of a refrigerant under-charged unit:
• Low subcooling
• Higher than normal discharge superheat
• Bubbles in EXV sight glass
• Low liquid level diagnostic
• Larger than normal evaporator approach temperatures (leaving water temperature
- saturated evaporator temperature)
• Low evaporator refrigerant temperature limit
• Low refrigerant temperature cutout diagnostic
• Fully open expansion valve
• Possible whistling sound coming from liquid line (due to high vapor velocity)
• High condenser + subcooler pressure drop
Some symptoms of a refrigerant over-charged unit:
• High subcooling
• Evaporator liquid level higher than centerline after shut down
• Larger than normal condenser approach temperatures (entering condenser satu-
rated temperature – entering air temperature)
• Condenser pressure limit
• High pressure cutout diagnostic
• More than normal number of fans running
• Erratic fan control
• Higher than normal compressor power
• Very low discharge superheat at startup
• Compressor rattle or grinding sound at startup
Some symptoms of an oil over-charged unit:
• Larger than normal evaporator approach temperatures (leaving water temperature
- saturated evaporator temperature)
• Low evaporator refrigerant temperature limit
• Erratic liquid level control
• Low unit capacity
• Low discharge superheat (especially at high loads)
• Low liquid level diagnostics
• High oil sump level after normal shut down
Some symptoms of an oil under-charged unit:
• Compressor rattle or grinding sound
• Lower than normal pressure drop through oil system
• Seized or welded compressors