An inefficient compressor is usually indicated by ___ head pressure and ___ suction pressure.

• A. Higher than normal / lower than normal
• B. Lower than normal / higher than normal
• C. Higher than normal / higher than normal
• D. Lower than normal / lower than normal

Answer: (B)

An inefficient compressor typically shows low suction pressure and high head (discharge) pressure. The low suction pressure means the compressor isn’t pulling refrigerant into the evaporator as effectively, which can result from worn or leaky valves, reduced displacement, or an undercharged evaporator. At the same time, the high head pressure occurs because the compressor has to work harder to push refrigerant into the condenser, and the condenser must reject more heat due to the inefficient compression. Together, these two pressure patterns indicate the compressor isn’t moving refrigerant efficiently on the low side while overworking the high side. If the pressures show other patterns, they usually point to different issues such as condenser restrictions or undercharge.