What are the reasons for the car heater not getting hot?

[DeJaxon]

Car heater not getting hot may be due to damage in the engine's cooling system or the water pump impeller. Damage in the engine's cooling system: If the engine's cooling system is affected by airlock, it can cause the car's cooling circulation system to malfunction, leading to the heater not getting hot. If the heater's small radiator has a hot inlet pipe but a cold outlet pipe, it indicates a blockage in the small radiator that needs replacement. Damage to the water pump impeller: If the vehicle's water pump impeller is damaged or slipping, it reduces the water flow through the radiator, resulting in the heater not getting hot. A new water pump impeller needs to be replaced.