US Patent 10166838 Air conditioner for vehicle

When a refrigerant evaporation temperature of an interior evaporator cannot be set lower than a dew-point temperature of air flowing into the interior evaporator in a heating operation, a refrigerant circuit is switched to a normal heating operation mode in which a flow rate of the refrigerant flowing into the interior evaporator is set to zero by allowing the refrigerant to flow toward a bypass passage. In a case where the air cannot be dehumidified by the interior evaporator, an unnecessary heat exchange between the air and the refrigerant in the interior evaporator can be suppressed. Thus, the energy of the vehicle air conditioner can be effectively prevented from being wasted.