In a belt-driven non-hermetic compressor, which component is most likely leakage point after idle?

• A. Piston rings
• B. Gaskets
• C. O-rings
• D. Rotating shaft seal

Answer: (D)

When a belt-driven non-hermetic compressor sits idle, the most likely leakage path is the interface where the drive shaft exits the housing—the rotating shaft seal. This dynamic seal must keep refrigerant inside while the shaft turns, and over time, wear, aging, or improper seating can allow refrigerant to seep past the lip, especially after periods of idleness when lubrication and cushion effects are uneven. Piston rings are internal to the compression chamber and mainly become leakage sources under operating pressure; without that pressure, their leakage is much less likely. Static gaskets and O-rings seal joints, but they’re less prone to leakage simply from being idle, since they depend on pressure as well. The shaft seal is the primary barrier at the external interface and is most susceptible to leakage when the unit rests and then restarts.