Why is there hot air when the car does not turn on the air conditioner?

The reasons why the hot air conditioner is not turned on in the car are: 1, and the internal circulation mode is not turned on. In order to ensure the air circulation in the car, the air conditioner will automatically switch to the external circulation mode, and the outside air will become hot after passing through the engine compartment; 2. The temperature switch is not set to the coldest state. At this time, the air mixing damper is in the open state, and the heat of engine water temperature enters the car through the damper. It is normal for cars to have hot air without air conditioning. There is no need to panic. This car has a water thermometer. When the pointer reaches the middle position, it can use the temperature generated by the engine to blow into the car to form warm air, which is the direct reason why heating in winter is more fuel-efficient than turning on the air conditioner in summer.