Which symptom would indicate a faulty compressor in an HVAC system?

A faulty compressor in an HVAC system often results in unusually low suction pressure. This is significant because the compressor's primary function is to compress the refrigerant vapor and raise its pressure before sending it to the condenser. If the compressor is not functioning properly—whether due to wear, mechanical failure, or electrical issues—it may not compress the refrigerant effectively. Consequently, the suction pressure, which is the pressure of the refrigerant returning to the compressor, can drop below normal levels.

This symptom can impact overall system performance, leading to insufficient cooling and potential compressor damage if left unaddressed. Recognizing this sign is crucial for technicians when diagnosing issues within an HVAC system, as it directly relates to the efficiency and functionality of the compressor itself.

In contrast, increased system pressure typically suggests that something else in the system is malfunctioning, such as an overcharged system or a restriction in the refrigerant line. A consistent temperature swing often signals problems with the thermostat or the overall system balance rather than the compressor specifically. Higher than normal subcooling can indicate an overcharged system as well or a malfunction in the expansion device but does not directly point to a compressor issue.