What should be done if a sight glass indicates the refrigerant is low quality?

When a sight glass indicates that the refrigerant is of low quality, it typically means that the refrigerant could be contaminated or not in its proper state (such as being mixed with moisture or having too much oil). In such cases, replacing the refrigerant is necessary to ensure the system operates efficiently and avoids potential damage.

Contaminated refrigerants can cause issues such as poor system performance, increased compressor wear, and reduced cooling efficiency. By replacing the refrigerant, you restore the system to an optimal state, ensuring that the refrigerant is clean and functioning properly. It helps to prevent further complications that may arise from using degraded or low-quality refrigerant.

The other options, while they may sound plausible, do not effectively address the fundamental issue of low-quality refrigerant indicated by the sight glass. Increasing the refrigerant charge may not resolve contamination problems, checking the compressor for leaks is essential under different circumstances, and installing an additional filter might mitigate some issues but wouldn't rectify the immediate problem of low-quality refrigerant.