An obstructed expansion valve may be indicated by an incompletely cooled evaporator and what other symptom?

Correct Answer: Option A — frosting at the evaporator inlet

An obstructed expansion valve causes an immediate pressure drop across the restriction, flashing liquid refrigerant prematurely. This localized cooling effect produces frost or sweating directly at the evaporator inlet while leaving the remainder of the coil starved and insufficiently cooled.