HVAC Unit
With a heater that warms the air with heat from the engine and an evaporator that cools the air through the evaporation of a refrigerant gas, this creates a vehicle temperature environment according to the operation of the instrument panel.
Window defogging making use of the characteristic dehumidifying effect of lowering the temperature is another important function. So as to prevent window fogging, modern car air conditioning initially cools the air to a temperature quite a bit lower than the temperature set by the user. Later the temperature is adjusted to that set by passing part of the cooled air over the heater to warm it. By using humidity sensors to optimize the initial cooling temperature, it is possible to greatly reduce the operating rate of the compressor. Similarly, by using linear opening angle air dampers to freely set external air intake, it reduces the operating rate of the compressor and saves power.
