What is the reason why Passat b5 warm air is not hot?

Whether it is winter or hot weather, we always use air conditioning. Especially in the cold winter, we need to turn on the warm air to adjust the comfortable temperature inside the car. Let's talk about the problem of insufficient heating in the car. First of all, we need to briefly introduce the principle of air conditioning warm air. Different from air conditioning refrigeration, warm air is realized by the heat of engine antifreeze. The antifreeze circulating in the engine enters the small water tank in the evaporation box of the air conditioner through the pipeline, the flow valve and the circulation valve, and then the air flows to the small water tank through the blower. Because of the heat, the air becomes hot and is blown out through the air conditioner outlet. In this process, many electronic and mechanical components, such as air conditioning outlet sensor, evaporation box temperature sensor, flow valve, circulation valve, water temperature sensor, regulating device and so on. , may also take part in the work. If there is no warm air in the car, we need to determine whether the following air-conditioning outlets are air-cooled. If there is no wind, it may be that the blower is damaged, or the air conditioning filter element is dirty and blocked, or the damper motor is damaged, or the damper is stuck. Another situation is that there is wind at the air outlet, but it is not hot air. If the warm air is not hot, we need to check whether the engine water temperature is normal first. If it has been in a low temperature state and does not reach the working temperature, the warm air will definitely not be hot. At this time, it is necessary to pay attention to whether the thermostat has been in a state of large cycle, or whether the signal of the water temperature sensor is true. Second, we should focus on whether there is a big temperature difference between the inlet and outlet pipes in front of the heating water tank. If this happens, the heating water tank must be blocked and needs to be disassembled, cleaned or replaced. Thirdly, it depends on whether the flow rate and temperature of antifreeze entering the warm air water tank meet the requirements. The temperature is measured by infrared thermometer, and the comprehensive judgment is made by storing the diagnostic data and fault problems of the tester. Often the water pump is lost or damaged, and the warm air flow valve and antifreeze circulation valve are damaged. Fourth, it depends on whether the antifreeze system has air resistance. It often happens that there is no exhaust after replacing antifreeze. At this time, it is necessary to use a special cylinder pad to solve it. The above is the analysis of automobile heating problem, and I hope it will be helpful to everyone.