What symptoms indicate a low refrigerant charge in an air conditioning system?

A low refrigerant charge in an air conditioning system typically leads to low pressures within the system. When there is insufficient refrigerant, the vapor pressure in the evaporator decreases, which results in a low suction pressure. The discharge pressure may also be low because the compressor is not able to achieve the necessary compression ratios due to the lack of sufficient refrigerant to compress.

This situation can also lead to symptoms such as poor cooling effectiveness, as the evaporator coil does not absorb heat effectively without adequate refrigerant flow. It's crucial to monitor both suction and discharge pressures when diagnosing refrigerant levels to ensure the system operates efficiently.

The other options describe scenarios that do not align with the symptoms of a low refrigerant charge. High suction and discharge pressures might indicate overcharging or other issues rather than a shortage of refrigerant. Compressor overheating could occur for various reasons, but it is not a direct symptom typically associated only with low refrigerant levels. Excessive airflow might not correlate with refrigerant levels, but rather with other factors like fan speeds or ductwork characteristics. Each symptom needs to be carefully assessed in the context of overall system performance and refrigerant levels.