Vehicle HVAC system with auxiliary coolant loop for heating and cooling vehicle interior

A vehicle includes a heating, ventilation and air conditioning (HVAC) system for heating and cooling a passenger compartment. The HVAC system includes a refrigerant loop operable in a cooling mode and a heating mode, and an auxiliary coolant loop for heating and cooling at least a portion of the passenger compartment. The auxiliary coolant loop includes a pump for moving a coolant, within the auxiliary coolant loop, through a first heat exchanger coupled to the refrigerant loop via an expansion device in the cooling mode, a second heat exchanger positioned within the passenger compartment, and a third heat exchanger coupled to the refrigerant loop, and a flow control valve. The temperature of the coolant within the auxiliary coolant loop is controlled utilizing the flow control valve and the pump. The first and third heat exchangers may be in parallel for controlling the movement of coolant therebetween to control temperature.