RTAD-SVX01F-E4
77
Maintenance Procedures
Some symptoms of a refrigerant
over charged unit:
- High Subcooling
- Larger than normal condenser
approach temperatures (Entering
Condenser Saturated 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
- Low Refrigerant Temperature
Cutout diagnostic
- Very erratic liquid level control
- Low unit capacity
- Low discharge superheat
(especially at high loads)
- Compressor rattle or grinding
sound
- 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
- Low oil sump level after normal
shut down
- Lower than normal oil
concentrations in evaporator
R134a Field Charging
Procedure
Be certain that the electrical power
to the unit is disconnected before
performing this procedure.
WARNING! Position all electrical
disconnects in the "OPEN" position
and lock them to prevent injury or
death due to electrocution.
Refrigerant Charging
If the refrigerant charge needs to be
adjusted, be certain to monitor the
subcooling and superheat
measurements. The subcooling
needs to be between 6°C (10°F) and
12°C (20°F) when the unit is running
fully loaded. The ambient
temperature is between 24°C (75°F)
and 38°C (100°F) and the leaving
water temperature is between 5°C
(41°F) and 13°C (55°F).
Refrigerant and Oil Charge
Management
Proper oil and refrigerant charge is
essential for proper unit operation,
unit performance, and
environmental protection. Only
trained and licensed service
personal should service the chiller.
Some symptoms of a refrigerant
under charged unit:
- Low Subcooling
- 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)
- Possible low discharge superheat
at high loads
- High Con Subcooler
Pressure drop
