What is the reason why the warm air is not hot when the water temperature is normal?

The correct way to turn on the heater is to start the engine to warm up and wait for the engine temperature pointer to reach the middle position before turning on the heater. But if the warm air is not hot all the time, there should be something wrong with the heating system of the car. The system structure of automobile air conditioner heater is very simple. The following is the reason introduction: 1, the principle of simplicity first and complexity later: If the warm air is not hot, first consider whether the air-conditioning filter element has not been replaced for a long time, which is the simplest and most easily overlooked thing, because if the air-conditioning filter element is dirty and blocked, it will lead to much less wind blowing out, thus affecting the heating effect of the warm air. 2, insufficient antifreeze: it will also affect air conditioning heating. This is an indispensable medium for cooling the engine, and it is also a heat-conducting medium for heating the automobile air conditioner. After the antifreeze that absorbs the heat of the engine enters the heater tank, it will blow out the heated air of the heater tank, that is, hot air. 3. The warm air tank is blocked: antifreeze cannot enter the warm air tank or the flow becomes smaller, which will also affect air conditioning and heating. 4. Thermostat failure will also affect air conditioning heating: Thermostat is a tool to automatically adjust the temperature, similar to the valve of faucet, which changes the circulation range of water through the valve, thus adjusting the cooling capacity of the cooling system and ensuring the engine to work in a suitable temperature range. And if the thermostat fails, the main valve can't be opened, and the antifreeze can't dissipate heat through the water tank, which will lead to overheating of the engine.