System and method for detecting a refrigerant leak in an HVAC system operating in an idle mode

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

• receiving, from a leak detection sensor, a measurement indicative of a concentration of a refrigerant;
• determining, using a controller, that the HVAC system should operate in a leak diagnostic mode if a concentration of the refrigerant exceeds a gas concentration threshold, and wherein during the leak diagnostic mode the method further comprises:
• receiving, from a first loss of charge sensor, a first suction pressure of the refrigerant while a first compressor in a first refrigerant circuit is turned off;
• waiting for a first predetermined duration;
• receiving, from the first loss of charge sensor, a second suction pressure of the refrigerant while the first compressor is turned off;
• and
• determining that the first refrigerant circuit includes a refrigerant leak if a difference between the first suction pressure and the second suction pressure exceeds a suction pressure threshold value.

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

• a memory operable to store a suction pressure threshold value, a gas concentration threshold, and a first predetermined duration;
• a processor operatively coupled to the memory and configured to:
• receive, from a leak detection sensor, a measurement indicative of a concentration of a refrigerant;
• compare the concentration of the refrigerant to the gas concentration threshold;
• determine that the HVAC system should operate in a leak diagnostic mode if the concentration of the refrigerant exceeds the gas concentration threshold, wherein during the leak diagnostic mode the processor is configured to:
• receive, from a first loss of charge sensor, a first suction pressure of the refrigerant while a first compressor in a first refrigerant circuit is turned off;
• wait for the first predetermined duration;
• receive, from the first loss of charge sensor, a second suction pressure of the refrigerant while the first compressor is turned off;
• and
• determine that the first refrigerant circuit includes a refrigerant leak if a difference between the first suction pressure and the second suction pressure exceeds the suction pressure threshold value.