Possible problems in the cooling system are:
First, the thermostat is always open or opened too early, which makes the cooling system have a big cycle prematurely, and the outside temperature is very low. Especially when the car is driving, cold air quickly cools the antifreeze, the engine water temperature does not come up, and the warm air does not heat up.
Second, the water pump impeller is damaged or lost, so that the flow through the warm air small water tank is insufficient and the heat cannot come up.
Third, the engine cooling system has air resistance, which leads to 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 heating tank is very hot and the outlet pipe is very cold, this situation should be that the small heating tank is blocked and should be replaced.