There may be the following reasons:
1. The air conditioning filter element is dirty or blocked, which will cause the air blowing out to be much smaller, thus affecting the heating of the heater. Effect.
2. The thermostat is broken. The thermostat is always open or the thermostat is opened too early, causing the cooling system to undergo a large cycle prematurely. If the outside temperature is very low, the cold wind will blow when the car is driving. If the antifreeze cools down quickly, the engine water temperature will not rise and the heater air will not heat up.
3. The water pump impeller is damaged or lost, causing insufficient flow through the small warm air water tank and preventing heat from coming up. There is an air blockage in the engine cooling system. The air blockage causes poor circulation in the cooling system, causing the water temperature to be high and the warm air to be tepid.
4. The car's warm air uses a blower to blow the heat from the small warm air water tank into the cab. If the warm air water tank is blocked and the heat from the small warm air water tank cannot be dissipated, it will also As a result, the temperature of the warm air cannot rise.
5. If the knob is adjusted to the warm air position, the air volume is large enough, and the wind direction is normal, the cool air blowing out may be whether the control flap cable of the hot and cold air of the heater box has fallen off, and whether the warm air impeller has Damage, whether the flap has fallen off, etc. If the heater water valve is damaged, the coolant may not be able to enter the heater water tank, causing the heater to not heat up.
6. The small warm air water tank is blocked, causing the coolant to be unable to pass through the small water tank and causing the warm air to not be hot.
I hope it will be helpful to you and hope you will adopt it, thank you!