An apparatus comprising: a high side heat exchanger configured to remove heat from a refrigerant; a subcooler heat exchanger configured to receive the refrigerant from the high side heat exchanger ; a flash tank configured to store the refrigerant from the subcooler heat exchanger ; a first load ; and a first compressor ; the apparatus being configured to operate in a first and second mode of operation, wherein during a first mode of operation: the first load configured to use the refrigerant from the flash tank to cool a first space proximate the first load ; the first compressor configured to compress the refrigerant from the first load ; and wherein during a second mode of operation: the subcooler heat exchanger configured to: receive the refrigerant from the flash tank ; transfer heat from the refrigerant from the high side heat exchanger to the refrigerant from the flash tank ; and direct the refrigerant from the flash tank to the first compressor ; the first compressor configured to: compress the refrigerant from the subcooler heat exchanger ; and direct the compressed refrigerant from the subcooler heat exchanger to the first load to defrost the first load . a high side heat exchanger configured to remove heat from a refrigerant; a subcooler heat exchanger configured to receive the refrigerant from the high side heat exchanger ; a flash tank configured to store the refrigerant from the subcooler heat exchanger ; a first load ; and a first compressor ; the apparatus being configured to operate in a first and second mode of operation, wherein during a first mode of operation: the first load configured to use the refrigerant from the flash tank to cool a first space proximate the first load ; the first compressor configured to compress the refrigerant from the first load ; and wherein during a second mode of operation: the subcooler heat exchanger configured to: receive the refrigerant from the flash tank ; transfer heat from the refrigerant from the high side heat exchanger to the refrigerant from the flash tank ; and direct the refrigerant from the flash tank to the first compressor ; the first compressor configured to: compress the refrigerant from the subcooler heat exchanger ; and direct the compressed refrigerant from the subcooler heat exchanger to the first load to defrost the first load . the first load configured to use the refrigerant from the flash tank to cool a first space proximate the first load ; the first compressor configured to compress the refrigerant from the first load ; and wherein during a second mode of operation: the subcooler heat exchanger configured to: receive the refrigerant from the flash tank ; transfer heat from the refrigerant from the high side heat exchanger to the refrigerant from the flash tank ; and direct the refrigerant from the flash tank to the first compressor ; the first compressor configured to: compress the refrigerant from the subcooler heat exchanger ; and direct the compressed refrigerant from the subcooler heat exchanger to the first load to defrost the first load . the subcooler heat exchanger configured to: receive the refrigerant from the flash tank ; transfer heat from the refrigerant from the high side heat exchanger to the refrigerant from the flash tank ; and direct the refrigerant from the flash tank to the first compressor ; receive the refrigerant from the flash tank ; transfer heat from the refrigerant from the high side heat exchanger to the refrigerant from the flash tank ; and direct the refrigerant from the flash tank to the first compressor ; the first compressor configured to: compress the refrigerant from the subcooler heat exchanger ; and direct the compressed refrigerant from the subcooler heat exchanger to the first load to defrost the first load . compress the refrigerant from the subcooler heat exchanger ; and direct the compressed refrigerant from the subcooler heat exchanger to the first load to defrost the first load . <EOS>