What common problem can occur if an expansion valve is malfunctioning?

A malfunctioning expansion valve can indeed lead to refrigerant flooding or starving of the evaporator. The expansion valve controls the flow of refrigerant into the evaporator coil, and if it is not functioning properly, it may either allow too much refrigerant to flow into the evaporator (resulting in flooding) or not enough refrigerant (leading to starving).

Flooding can cause liquid refrigerant to enter the compressor, which may lead to serious damage, while starving means the evaporator coil won't receive enough refrigerant to absorb heat effectively, which can severely impact the cooling efficiency of the system. This makes it critical for the expansion valve to be operational to maintain the proper balance of refrigerant flow, ensuring the overall efficiency and reliability of the HVAC system.

The other options relate to issues that can arise in HVAC systems but are not the primary consequence of a malfunctioning expansion valve. High energy consumption can occur due to several factors, including system inefficiencies, but it's not a direct result of the expansion valve alone. An increase in refrigerant temperature or compressor failure, while serious issues, are typically results of other systemic problems that may arise if the expansion valve is not properly maintaining refrigerant flow but are not the direct or immediate consequence of its malfunction