Trane RTAC 140-500 ton units (60 Hz) User Manual
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.
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)
- 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)
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)
- 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