What is a common effect of a malfunctioning expansion valve?

A common effect of a malfunctioning expansion valve is frost accumulation in the evaporator. The expansion valve plays a critical role in regulating the flow of refrigerant into the evaporator. When the valve is not functioning correctly, it can either allow too much or too little refrigerant to flow into the evaporator coil.

If excessive refrigerant enters the evaporator, it may not have enough time or surface area to absorb heat effectively, leading to a drop in pressure and temperature. This condition can cause moisture in the air to freeze on the evaporator coil, resulting in frost or ice accumulation. Conversely, if too little refrigerant flows into the evaporator, the coil may not cool properly, which can also contribute to unusual icing patterns under certain circumstances.

Understanding this behavior is essential, as it helps in diagnosing and troubleshooting issues within refrigeration systems. The other options do not accurately reflect typical outcomes associated with a malfunctioning expansion valve. For instance, a functioning expansion valve does not improve compressor efficiency or refrigerant flow, nor does it enhance cooling performance directly when it malfunctions.