Question 71Refrigeration & AC - 1st Asst/Chief

The correct answer is B) low pressure in the evaporator at low load. Surging in a centrifugal air conditioning compressor is caused by a low pressure condition in the evaporator at low load. When the compressor is operating at low load, the low pressure in the evaporator can cause the airflow through the compressor to become unstable, leading to surging. This instability can cause the compressor to experience pressure fluctuations, vibrations, and potential damage. The other answer choices are incorrect because low pressure in the condenser or high load conditions in the evaporator would not directly lead to surging in the centrifugal compressor. Surging is specifically caused by the low pressure condition in the evaporator during low load operation.