A system with a leak in the liquid line was repaired, evacuated, and recharged. When started, the compressor is noisy and running hot. The most probable cause is...

• A. Low oil in the system
• B. Overcharge of refrigerant
• C. Dirty condenser
• D. Fan belt slipping

Answer: (A)

The noisy, hot-running compressor points to lubrication problems. When the liquid-line leak was repaired and the system was evacuated and recharged, oil that lubricates the compressor can be lost or not properly returned to the compressor crankcase. If the oil charge ends up too low, the bearings and rotating parts don’t get enough lubrication, causing more friction, louder operation, and increased heat as the compressor works harder. Other issues like an overcharge, a dirty condenser, or a slipping fan belt would produce different symptoms (such as unusually high pressures, poor heat rejection, or belt noise) rather than the combination of loud operation and overheating caused by insufficient lubrication.