Automotive Service Excellence (ASE) Air Conditioner Certification Practice Exam 2026 - Free ASE Air Conditioner Practice Questions and Study Guide

A clogged expansion valve plays a crucial role in the efficiency and performance of an A/C system by controlling the amount of refrigerant that flows into the evaporator. When the expansion valve is obstructed, it restricts refrigerant flow to the evaporator coil. This leads to insufficient refrigerant reaching the evaporator, which in turn affects its ability to absorb heat effectively.

As a result, the temperature in the evaporator will be negatively impacted. A lower flow of refrigerant means that the evaporator cannot lower the temperature of the air passing through it effectively, leading to warmer air being delivered from the vents. This ultimately reduces the overall cooling performance of the system.

Understanding the function of the expansion valve and the consequences of a clog is vital for diagnosing A/C issues. A clogged valve results in failures within the cooling cycle, which manifests as a rise in the temperature of the evaporator and poor cooling output from the AC system.