HVAC - EPA Certification Practice Exam

The warning regarding hermetic compressors under deep vacuum emphasizes the importance of ensuring that the discharge service valve is closed before energizing the compressor. When the discharge service valve is open, the compressor can operate in an unsafe manner, leading to a risk of damage or failure. In this scenario, the compressor may not build the necessary pressure, which could cause overheating and affect its internal components due to insufficient refrigerant flow and lubrication. Hermetic compressors are designed to work within specific pressure and temperature parameters. If the discharge service valve is open while the compressor is energized, it fails to provide the necessary resistance against the refrigerant’s flow, potentially causing the compressor to run dry. This situation can lead to significant damage, including burnout of the motor or mechanical failure. Maintaining proper operation requires that the compressor is not energized under such conditions to ensure its longevity and safety, highlighting the critical nature of this warning in HVAC practices.