What are the reasons for the insufficient heating in the Volkswagen Santana?

[SiennaRose]

The reasons for the insufficient heating in the Volkswagen Santana are: 1. The thermostat is constantly open or opens too early, causing the cooling system to circulate excessively and resulting in low external temperatures; 2. The water pump impeller is damaged or slipping, leading to insufficient flow through the heater core and low heat output; 3. There is air trapped in the engine cooling system, causing poor circulation and resulting in high water temperature but insufficient heating. The solutions for the insufficient heating in the Volkswagen Santana are: 1. Replace the water pump impeller; 2. Clean and unclog the engine cooling system; 3. Install or replace the thermostat. The principle of vehicle heating is that during heating, the high-temperature coolant from the engine flows through the heater core, and the air blown by the blower also passes through the heater core, allowing warm air to be blown out from the car's air conditioning vents.