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Chiller/Heat Pump Troubleshooting
5. Symptom: Compressor loses oil
Possible Causes
Oil trapped in the system
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
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 tubing 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 condenser temperature
Low suction pressure
Condenser pressure regulating valve(if provided) not properly adjusted
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Potential Solutions
Check operating condition to assure compressor runs inside map.
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 condensing temperature; Check control valves on condenser.
Raise set point; check design specification.
Refrigerant charge; replace compressor.
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
Check EXV settings and functionality.
Reclaim excess refrigerant and verify proper sub-cooling and superheat.
Low refrigerant charge; faulty; excessive load 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'.
Refer to OEM manufacturer manual for default settings; replace condenser
head pressure control valve (if installed).
ARTC-SVX010A-EN
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