Refrigerant leak mitigation using isolation valves

A method of operating heating, ventilation, and air conditioning (HVAC) system, the HVAC system comprising:

• performing a pump down cycle comprising:
• transmitting, to a compressor, a first signal that causes the compressor to be turned on or stay turned on to transfer at least a portion of a refrigerant from an indoor heat exchanger to an outdoor heat exchanger to reduce a refrigerant charge in an indoor section of the HVAC system;
• transmitting, to a vapor line isolation valve, a second signal that causes the vapor line isolation valve to open;
• transmitting, to a liquid line isolation valve, a third signal that causes the liquid line isolation valve to close;
• determining that the refrigerant charge in the indoor section of the HVAC system has decreased to be less than a threshold value;
• and
• in response to determining that the refrigerant charge in the indoor section of the HVAC system has decreased to be less than the threshold value:
• turning off the compressor;
• and
• closing the vapor line isolation valve.

A controller of a heating, ventilation, and air conditioning (HVAC) system, the controller comprising:

• a memory configured to store pump down instruction for performing a pump down cycle;
• and
• a processor communicatively coupled with the memory, and configured to:
• transmit, to a compressor, a first signal that causes the compressor to be turned on or stay turned on to transfer at least a portion of a refrigerant from an indoor heat exchanger to an outdoor heat exchanger to reduce a refrigerant charge in an indoor section of the HVAC system;
• transmit, to a vapor line isolation valve, a second signal that causes the vapor line isolation valve to open;
• transmit, to a liquid line isolation valve, a third signal that causes the liquid line isolation valve to close;
• determine that the refrigerant charge in the indoor section of the HVAC system has decreased to be less than a threshold value;
• and
• in response to determining that the refrigerant charge in the indoor section of the HVAC system has decreased to be less than the threshold value:
• turn off the compressor;
• and
• close the vapor line isolation valve.