1。 The thermostat is always on or opened too early, which makes the refrigeration system cycle too early. Moreover, the temperature outside is very low, especially when the car is driving, cold air will quickly cool the antifreeze, the engine water temperature will not come up, and the warm air will not be hot.
2. The water pump impeller is damaged or lost, so that the flow through the small warm air water tank is not enough, and the heat can't come up.
3, the engine cooling system has air resistance, resulting in poor circulation of the cooling system, resulting in high water temperature and lukewarm air. If there is air in the cooling system all the time, it is likely that the cylinder pad is damaged and the cooling system is blown by air. If the inlet pipe of the small heating tank is very hot and the outlet pipe is very cold, it means that the small heating tank is blocked and needs to be replaced.