How to maintain gl8 commercial vehicle without warm air?

the vehicle heating system is not hot, which can be divided into two reasons, one is caused by the engine cooling system, and the other is caused by the poor operation of the heating control mechanism. During maintenance, we should first determine which reason is caused, and then carry out corresponding maintenance. The method of discrimination is very simple. Look at the temperatures of the two inlet pipes of the warm air small water tank. If both pipes are hot enough, it means that it is a problem with the air flow control mechanism. On the contrary, if both pipes are cold, or one is hot and the other is cold, it means that it is a problem with the cooling system. The possible problems of the cooling system are as follows: First, the thermostat is always open or the thermostat is opened too early, which makes the cooling system carry out a large cycle too early, and the external temperature is very low, especially when the car runs, the cold wind will quickly cool the antifreeze, the engine water temperature will not come up, and the warm air will not be hot. Second, the impeller of the water pump is damaged or lost, which makes the flow through the warm air small water tank insufficient and the heat can't 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 not hot warm air. If there is always gas in the cooling system, it is likely that cylinder gasket is damaged and leaks gas into the cooling system; If the inlet pipe of the small warm air tank is very hot and the outlet pipe is cold, this situation should be that the small warm air tank is blocked and should be replaced. The car's warm air is blown into the cab by the blower. If the air volume is not enough or the cold and hot air distribution is not good, the heat of the warm air tank will not be radiated, and the temperature of the warm air will not come up. At this time, first check whether the filter is dirty and blocked, clean it, and replace it in time if necessary; Then check the operation of each gear of the blower, and each gear must reach sufficient speed. If the knob is adjusted to the warm air position, the air volume is large enough, the wind direction is normal, and the cool air is blown out, check whether the control flap cable of cold and hot air in the warm air box falls off, whether the warm air impeller is damaged, whether the flap falls off, etc., and the warm air will heat up after troubleshooting.