ABSTRACT In electric vehicles (EVs) the thermal systems (cooling and HVAC) are significantly more complex than conventional vehicles. EV design presents the additional challenge of optimizing electrical energy usage to meet thermal management demands of the cabin and powertrain. An EV is being developed which employs a range of devices to provide heating and cooling for the cabin, powertrain and battery, including an electric compressor and direct air Positive Temperature Coefficient (PTC) heater. This paper discusses the integrated control system developed to balance the complex thermal system demands.