🔍 Key Concepts

• Mechanical wear in compressors and how it affects noise and vibration • Refrigerant and oil behavior in the system (floodback, slugging, circulation) • How multiple different faults can sometimes produce similar symptoms like noise

💭 Think About

• For each option, ask yourself: would this condition reasonably create knocking, rattling, or unusual mechanical sounds inside a compressor? Why or why not? • Think about what happens if liquid refrigerant or excess oil enters the compressor cylinders instead of vapor—how would that sound mechanically? • Consider whether exam questions about troubleshooting often focus on a single cause, or whether they sometimes group several related causes under one choice.

✅ Before You Answer

• For each listed condition, visualize the mechanical interaction inside the compressor (bearings, pistons, valves) and whether it could cause noise. • Ask: does wear in moving parts (like bearings and pins) usually lead to quiet or noisy operation? • Confirm whether slugging/floodback is known to cause loud knocking or hammering sounds due to incompressible liquid entering the compressor.