Trane Thermafit AMC Series Installation, Operation And Maintenance Manual page 72

Chiller Troubleshooting
5. Symptom: Compressor loses oil
Possible Causes
Oil trapped in line
Compressor short cycling
Liquid refrigerant
6. Symptom: Low refrigeration suction pressure
Possible Causes
Lack of refrigerant
Evaporator dirty
Suction line blockage
Condensing temperature too low
Low water temperature
Incorrect fan speed
Low discharge pressure
Improper expansion valve settings
Mis-adjusted or defective TXV
Receiver service valve closed
Clogged liquid line filter-drier
Excessive glycol concentration
Liquid line solenoid restricted or faulty
Insufficient chilled water
Restricted water/glycol line
Water/glycol mixture contaminated
Evaporator clogged or fouled
7. Symptom: High refrigeration suction pressure
Possible Causes
Expansion valve opened too far
Excessive refrigerant charge
High water temperature
8. Symptom: Low refrigerant discharge pressure
Possible Causes
Insufficient refrigerant in chiller
Faulty compressor
Low ambient conditions
Low suction pressure
72
Potential Solutions
Low refrigerant velocity caused by operation outside operating envelope.
Adjust proper control settings for Min. ON/OFF runtime.
Check compressor superheat. Superheat at the compressor suction should be
approximately 12°F (8.3°C).
Potential Solutions
Check for leaks. Repair and add charge.
Clean with chemical.
Check suction line for any obstacle.
Check fan settings.
Raise set point; check design specification.
Check fan settings.
Refrigerant charge; replace compressor, check fan settings.
Check EXV functionality and settings.
Adjust or replace valve.
Turn counterclockwise completely. Do not fully backseat if pressure switch is
installed on service port.
Replace filter drier or cartridges.
Charge to proper glycol concentration.
Replace solenoid valve, coil, or internals as necessary.
Adjust flow rate through evaporator.
Clean strainers; check manual and electronic valves.
Intensive cleanup effort needed to identify source of contamination; external
filter may be required.
Reverse flush with appropriate chemical solutions.
Potential Solutions
Re-adjust to 10° to 12°.
Creates high pressure alarms; reclaim excess refrigerant and verify proper
sub-cooling and superheat.
Low refrigerant charge; failing compressor; check design specifications.
Potential Solutions
Check for leaks. Repair and add refrigerant as needed.
Check compressor.
Check condenser rating tables.
See "low refrigeration suction pressure".
ARTC-SVX008A-EN