Controller for defogger

A controller for a defogger including a heating wire disposed on a window glass of a vehicle, the controller comprising:

• a storage device;
• and
• processing circuitry configured to:
• turn on the defogger;
• repeatedly acquire a value of current flowing through the heating wire while the defogger is on;
• repeatedly calculate a total accumulated power consumption while the defogger is on, the total accumulated power consumption being a total of power consumed by the defogger from when the defogger is turned on;
• turn off the defogger when the total accumulated power consumption is greater than or equal to a power threshold value and the value of the current has converged to a constant value;
• acquire a temperature and a humidity outside the vehicle at a point in time when the defogger is turned on;
• determine whether the defogger has been turned on again within a preset period from when the defogger was turned off based on the value of the current having converged to the constant value;
• store, as failure data in the storage device, the temperature, the humidity, and the power threshold value acquired at a time the defogger was turned on when the defogger has been turned on again within the preset period, wherein the preset period is less than one minute;
• and
• acquire, from a map stored in the storage device, the power threshold value corresponding to the acquired temperature and the acquired humidity.