A heating, ventilation, and air conditioning (HVAC) system includes a condenser, an evaporator, and a first refrigerant circuit. The first refrigerant circuit includes a first compressor configured to receive refrigerant, a first circuit of condenser coils positioned in the condenser and configured to receive refrigerant from the first compressor, a first controllable valve, and a first pressure relief valve positioned upstream of the first controllable valve and downstream of the first compressor to vent refrigerant when a predetermined pressure threshold is exceeded. At least a first loss of charge sensor measures a first loss of charge parameter of refrigerant flowing through the first refrigerant circuit. A controller stores a loss of charge threshold, receives the first loss of charge parameter, and determines a refrigerant leak based on a comparison. In response, the controller operates a pump down mode to evacuate refrigerant from the refrigerant circuit.