Why is the air conditioner not hot when the heater is turned on?

The reasons why the vehicle heating system is not hot can be divided into two aspects. One is caused by the engine cooling system, and the other is caused by the poor working of the heating control mechanism. When repairing, we must first determine whether Which aspect caused it, then carry out corresponding repairs. The method of identification is very simple. Look at the temperature of the two water inlet pipes of the small heater water tank. If both pipes are hot enough, it means there is a problem with the air volume control mechanism. On the contrary, if both pipes are cold, or one pipe is hot and the other is hot. If it is cold, it means there is a problem with the cooling system.

Possible problems in the cooling system are:

First, the thermostat is always open or the thermostat is opened too early, causing the cooling system to undergo a large cycle prematurely, and the external temperature It is very low, especially when the car is running, the cold air will quickly cool down the antifreeze, the engine water temperature will not rise, and the warm air will not heat up.

The second is that the water pump impeller is damaged or lost, causing insufficient flow through the small warm air water tank and preventing heat from coming up.

Third, there is air blockage in the engine cooling system. The air blockage leads to poor circulation of the cooling system, causing high water temperature and lack of warm air. If there is always air in the cooling system, it is likely that the cylinder gasket is damaged and air is flowing into the cooling system; if the water inlet pipe of the small heater water tank is very hot and the water outlet pipe is cold, this situation should be that the small heater water tank is blocked. , the small heater water tank should be replaced.

The car's warm air uses a blower to blow the heat from the small warm air water tank into the cab. If the air volume is not enough or the hot and cold air distribution is not good, the heat from the small warm air water tank cannot be dissipated. It will also cause the temperature of the warm air to not rise. At this time, first check whether the filter is dirty and clogged, 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 cool air blows out, you should check whether the cables of the hot and cold air control flaps of the heater box have fallen off, whether the warm air impeller is damaged, whether the flaps have fallen off, etc. After troubleshooting, the heater will heat up.