Bad compressor valves have plagued HVAC systems for ages. As with any moving part, valves wear down over time, allowing refrigerant to push past the seals and throw the system off balance. Often this leads to flooding and other conditions that cause the compressor to function less efficiently than it should. However, it can be very difficult to diagnose this issue from the outside because there are no visible indications that the compressor is suffering. That's why you need to call in an experienced technician who can solve the problem, right down to the compressor core.