A unitary heat pump air conditioner system, comprising: a cold coolant loop, a hot coolant loop, a refrigerant loop including: a condenser configured to condense a hot compressed refrigerant into a liquid refrigerant, an expansion device configured to receive and partially expand the liquid refrigerant from said condenser into a vapor-liquid phase refrigerant, an evaporator downstream of said expansion device configured to evaporate the vapor-liquid phase refrigerant into a cold vapor refrigerant and is in thermal communication with said cold coolant loop having an external heat exchanger, and a compressor configured to receive and compress the cold vapor refrigerant from said evaporator into the hot compressed refrigerant to said condenser, wherein said refrigerant loop includes means to selectively divert at least a portion of said hot compressed refrigerant exiting from said compressor to said evaporator; the refrigerant loop in thermal communication with said cold coolant loop and said hot coolant loop; the cold coolant loop includes a cold heat exchanger in thermal communication with the evaporator; a refrigerant diversion loop hydraulically connecting the hot compressed refrigerant exiting from said compressor to the inlet of the evaporator downstream of the expansion device, wherein said means to selectively divert at least a portion of said hot compressed refrigerant includes a proportioning valve in said refrigerant loop between said compressor and said condenser, wherein said proportioning valve is operative to divert between zero to 100 percent of said hot compressed refrigerant exiting from said compressor to said evaporator, wherein said refrigerant diversion loop hydraulically connects said proportioning valve to an inlet of said evaporator, wherein said refrigerant loop includes a bypass valve positioned downstream of said condenser and upstream of said expansion device, wherein said bypass valve is operative to bypass the liquid refrigerant exiting said condenser to said diversion loop when said proportioning valve is diverting less than 100 percent of hot compressed refrigerant from said compressor. a cold coolant loop, a hot coolant loop, a refrigerant loop including: a condenser configured to condense a hot compressed refrigerant into a liquid refrigerant, an expansion device configured to receive and partially expand the liquid refrigerant from said condenser into a vapor-liquid phase refrigerant, an evaporator downstream of said expansion device configured to evaporate the vapor-liquid phase refrigerant into a cold vapor refrigerant and is in thermal communication with said cold coolant loop having an external heat exchanger, and a compressor configured to receive and compress the cold vapor refrigerant from said evaporator into the hot compressed refrigerant to said condenser, a condenser configured to condense a hot compressed refrigerant into a liquid refrigerant, an expansion device configured to receive and partially expand the liquid refrigerant from said condenser into a vapor-liquid phase refrigerant, an evaporator downstream of said expansion device configured to evaporate the vapor-liquid phase refrigerant into a cold vapor refrigerant and is in thermal communication with said cold coolant loop having an external heat exchanger, and a compressor configured to receive and compress the cold vapor refrigerant from said evaporator into the hot compressed refrigerant to said condenser, wherein said refrigerant loop includes means to selectively divert at least a portion of said hot compressed refrigerant exiting from said compressor to said evaporator; the refrigerant loop in thermal communication with said cold coolant loop and said hot coolant loop; the cold coolant loop includes a cold heat exchanger in thermal communication with the evaporator; a refrigerant diversion loop hydraulically connecting the hot compressed refrigerant exiting from said compressor to the inlet of the evaporator downstream of the expansion device, wherein said means to selectively divert at least a portion of said hot compressed refrigerant includes a proportioning valve in said refrigerant loop between said compressor and said condenser, wherein said proportioning valve is operative to divert between zero to 100 percent of said hot compressed refrigerant exiting from said compressor to said evaporator, wherein said refrigerant diversion loop hydraulically connects said proportioning valve to an inlet of said evaporator, wherein said refrigerant loop includes a bypass valve positioned downstream of said condenser and upstream of said expansion device, wherein said bypass valve is operative to bypass the liquid refrigerant exiting said condenser to said diversion loop when said proportioning valve is diverting less than 100 percent of hot compressed refrigerant from said compressor.