What should be checked if a compressor is not starting in a heat pump system?

When a compressor in a heat pump system is not starting, checking the fuses and breakers is crucial because these components serve as the primary electrical protection for the compressor. If a fuse is blown or a breaker has tripped, the compressor will not receive the necessary electrical power to start. This is often one of the simplest and quickest checks to perform, as it involves visually inspecting the fuses and resetting any tripped breakers, which can sometimes resolve the issue without further troubleshooting.

While the other factors, such as capacitor health, temperature of the refrigerant, and charge amount, are important in assessing the overall functionality of the heat pump, they are typically not the first checks to perform when a compressor fails to start. Capacitors can affect the starting capability of the compressor, but if there’s no power due to electrical interruptions, the capacitors would not be the first focus. Likewise, the temperature of the refrigerant and the charge amount are more relevant to the operation once the compressor starts; they wouldn't prevent the compressor from receiving power initially.