Car blowers blow when it is hot, but not when it is cold. Why?

If the heating is not hot in winter, first check whether there is a lack of antifreeze. If there is no shortage of antifreeze, check whether there is a problem with the blower and whether the radiator fan rotates. The reason for checking the above items is that the warm air in winter does not take the air conditioning system, but uses the heat from the engine cooling system to blow into the cab for heating. Therefore, the above are the most basic and common reasons why warm air is not hot, and self-test without instruments is also possible.