A compressor with proper voltage and a hard start relay and capacitor draws lock rotor amps on startup. What is the most likely problem?

When a compressor draws lock rotor amps at startup, it indicates that the compressor is not able to start properly and is stuck in the locked rotor condition. In this particular scenario, if the voltage is correct and a hard start relay and capacitor have been installed, the most likely issue is that the potential relay is open.

The potential relay is responsible for disconnecting the start winding once the compressor reaches a certain speed, allowing it to then run on the run winding. If this relay fails to close (i.e., it remains open when it shouldn't), the start winding does not receive the necessary current to help the compressor start, causing the compressor to draw excessive current and potentially preventing it from starting altogether.

In contrast, options like the unit being overcharged or having an open winding would lead to different symptoms. Overcharging typically causes high pressure issues, while an open winding would not allow the compressor to draw current at all. A pressure difference that is too great can result from other issues but would not necessarily lead to the specific symptoms indicated by the lock rotor amps being drawn. Therefore, the condition of the open potential relay aligns perfectly with the symptoms observed in the question.