Compressor Overheating:
Typically caused by high compression ratios due to system malfunctions.
High heat from compression causes oil breakdown, leading to:
Part wear and seizing
Carbon deposits forming on components
Symptoms and Clues:
Lubrication Breakdown:
Friction damage to compressor piston rings.
Scoring of the piston.
Carbon Deposits:
Can plug strainers or clog filter dryers.
Dark deposits on valve plates indicate overheating.
Causes and Remedies:
High Condensing Temperatures and Compression Ratios:
Check for low condenser airflow; clean if necessary.
Inspect fans and refrigerant charge (overcharge or undercharge issues).
Cure: Check subcooling and for non-condensables in the system.
Use proper installation and service procedures, including using a vacuum pump with a good micron gauge.
High Discharge Temperatures:
Discharge line temperature 6 inches away from the compressor exceeding 225°F indicates internal compressor temperatures around 300°F.
This causes oil breakdown and burning.
Cure: Maintain proper suction pressure and keep suction gas temperature below 65°F, 6 inches from the service valve.
Summary:
Low suction pressure and high superheat both cause high discharge and internal compressor temperatures, leading to oil breakdown.
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