Audi a6 can't get hot air. What's the matter?

There are four reasons why Audi a6 does not emit hot air: 1. The heater regulating mechanism is not working properly: check the temperature of the two inlet pipes of the heater tank. If both pipes are basically hot enough, the regulating mechanism is out of order and the relevant parts need to be replaced. 2. The thermostat is always on or turned on too early: the cooling system is put into large circulation too early, and the outside temperature is very low, especially when the car is driving, the cold air cools the coolant quickly, the engine water temperature does not come up, and the warm air may not be hot. 3. The impeller of the water pump is damaged or lost: the flow through the warm air small water tank is not enough, so the heat can't come up. 4. There is air resistance in the engine cooling system: air resistance affects the poor circulation of the cooling system, resulting in high water temperature and no warm air. If there is gas in the cooling system all the time, it is likely that the cylinder pad is damaged and the gas leaks into the cooling system; If the inlet pipe of the small warm air tank is very hot and the outlet pipe is very cold, this situation should be that the small warm air tank is blocked. The small heater water tank should be replaced.