The surging that occurs in a centrifugal air conditioning compressor is a result of what conditions?

Correct Answer: Option B — low pressure in the evaporator at low load

Centrifugal compressor surge occurs when evaporator refrigeration load drops significantly while condenser pressure remains high. The reduced vapor volume entering the impeller fails to maintain stable axial flow, causing flow reversal, severe vibration, and aerodynamic stalling within the compressor.