There are several reasons why a car may not have heating: 1. Clogged heater core. The internal structure of a car's heater core consists of many small heat dissipation tubes, making it prone to internal blockages. Scale, impurities, flocculants, and sediment in the coolant can all cause blockages. Once the heater core is clogged, the flow rate of the coolant inside slows down, the volume decreases, and insufficient heat is provided, resulting in the heating system not producing warm air. 2. Thermostat failure. If the thermostat is stuck open, the coolant circulates in a large loop from the moment the engine idles. In northern winter conditions, the water temperature will remain low for an extended period and fail to rise, causing the heating system to produce no warm air. This can also be observed on the water temperature gauge, where the needle is significantly below the normal level. 3. Heater valve failure. When the heater valve malfunctions, the electronically controlled valve no longer responds to the computer's commands, remaining stuck in a fully open, fully closed, or fixed position. In this case, no coolant flows through the heater core, or the flow rate is uncontrolled, leading to unregulated heating temperature. The heater valve is essentially an electronically controlled valve. It is installed between the inlet pipe of the heater core and the engine's small circulation loop. The air conditioning computer controls the valve's opening and closing to regulate the flow of coolant into the heater core, achieving more precise control of the heating temperature.
