A temperature regulation system for air inside of a vehicle regardless of the on/off state of the vehicle's ignition or engine includes a rechargeable battery for supplying power to an air moving system and a heat exchanger in accordance with demand signals from a thermostat. A motor-generator has a motor mode wherein electrical energy from the battery is converted into rotational kinetic energy and coupled to an AC compressor, and a generator mode wherein rotational kinetic energy from the engine is converted into electrical energy to recharge the battery. A control circuit is electrically connected with the motor-generator and adapted to activate the motor mode when the engine is off and the air temperature inside the vehicle exceeds the desired temperature range, the motor-generator otherwise being in the generator mode. Alternate embodiments includes a motor-compressor that replaces the stock compressor of the vehicle.