Patent ID: 8047274

Claim:
An air conditioner for a vehicle, comprising: a main heater for heating air in a vehicle compartment, using coolant of an engine of the vehicle as a heat source; an auxiliary heater for heating air in the vehicle compartment, using a heat source other than exhaust heat of the engine; means for outputting a requirement signal for requiring startup of the engine when a temperature of the coolant of the engine is determined to be lower than a threshold; and means for adjusting the threshold based on an operating state of the auxiliary heater such that as an amount of heat generated by the auxiliary heater increases, the threshold is decreased, wherein when a target temperature (TAO) to be blown into the vehicle compartment is lower than a first temperature, the requirement signal is not output by the outputting means, when the target temperature is equal to or higher than the first temperature and lower than a second temperature that is higher than the first temperature, the threshold is increased as the target temperature increases, and when the target temperature is equal to or higher than the second temperature, the threshold is a constant value, and the constant value is set to be decreased as the amount of heat generated by the auxiliary heater increases.