Why is there no hot air blowing out from the air conditioner?

[VanAlana]

There are several reasons why a car's air conditioner may not produce hot air: 1. Thermostat failure: The water temperature fails to rise, resulting in no hot air. 2. Heater valve failure: When the heater valve malfunctions, the opening of the electronically controlled valve is no longer managed by the computer, remaining either permanently open, permanently closed, or stuck in a fixed position. In such cases, the heater core either has no coolant flow or the flow is uncontrolled, leading to unregulated air conditioner heating. 3. Heater core blockage: If the heater core is blocked, the flow rate of the coolant inside slows down, reducing the volume of flow. This insufficient heat supply naturally results in the air conditioner's hot air not being warm enough.