What indicates an inefficient compressor in terms of pressure readings?

In evaluating the efficiency of a compressor based on pressure readings, it's important to understand the relationship between head pressure and suction pressure in a properly functioning system. The correct answer indicates that if the head pressure is higher than normal while the suction pressure is low, it signifies that the compressor is struggling to circulate refrigerant effectively.

A higher than normal head pressure usually occurs when there is a blockage or restriction in the system, causing the compressor to work harder to push the refrigerant through the system. At the same time, a low suction pressure suggests that the compressor is not able to draw in sufficient refrigerant, which can be an indication of issues such as a leak, excessively low refrigerant levels, or problems with the evaporator coil. Together, these conditions suggest an imbalance in the refrigerant cycle, highlighting compressor inefficiency and possible failure.

In contrast, conditions described in the other options—where the pressures either remain normal or where the suction pressure does not correspond to high head pressure—do not typically indicate compressor inefficiency. In a well-functioning system, high and low pressures should be within expected parameters relative to one another, aligning with the cooling needs of the application.