What is the function of the AC when the defog switch is turned on?

The function of the air conditioning (AC) system when the defog switch is activated is to turn on. This is because the AC helps to remove humidity from the air inside the vehicle, which is essential for defogging the windshield. When the defogger is engaged, the AC works in conjunction with the heating system to ensure that the air blowing onto the windshield is dry and warm, effectively clearing any fog or condensation that has accumulated.

This function is particularly important in colder conditions, where moisture in the air can lead to significant fogging. By turning on the AC, the vehicle can maintain better visibility and a safer driving experience.