High suction pressure and low discharge pressures may indicate what issue?

When analyzing a system with high suction pressure and low discharge pressure, the indication of defective compressor valves is significant. The compressor operates by compressing the refrigerant from a low pressure (suction side) to a high pressure (discharge side). If the valves are not functioning correctly— for instance, if they are stuck open or not sealing properly— refrigerant can bypass the compression process. This results in an inability to achieve the necessary discharge pressure, leading to low discharge pressure readings while the suction pressure remains high.

High suction pressure indicates that the refrigerant is not being adequately compressed and is instead accumulating in the evaporator or suction line. Coupled with low discharge pressure, this scenario typically points to an issue with the compressor's ability to properly compress the refrigerant because the exhausted refrigerant is not being expelled as intended.

The other options suggest different issues:

• An overcharge of refrigerant would typically lead to high pressure on both the suction and discharge sides, as excess refrigerant can cause flooding.
• A low refrigerant charge would lead to low suction pressure and potentially normal or slightly elevated discharge pressure due to reduced refrigerant mass flow.
• A high compression ratio is characterized by a large difference between suction and discharge pressures, but this would not