Heater: DIY renewal, repair and maintenance - manuals and video tutorials

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How to change blower motor on SKODA OCTAVIA 2 (1Z3) TUTORIAL | AUTODOC

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Published on: 27/04/2016

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Common questions about checking and repairing the car heater system

Why does the car heater system fail?

The car heater system stops functioning if even one of its components fails. The thermostat may get stuck due to the use of poor quality coolant. The HVAC control unit and the relay may burn out as a result of faulty wiring. The pipes and radiator of the heater lose their tightness over time, which leads to coolant leaks and airing of the system. Clogged air ducts, a bad cabin filter, or damage to the flaps or blower mean less warm air enters the passenger compartment. A stuck water pump cannot circulate the coolant.

Why does the heater system only work when driving?

The car heating system’s operation directly depends on the operation of the engine cooling system. Antifreeze circulates through its radiator and pipes. The water pump, which is driven by a belt, is responsible for its supply. The belt only starts moving when the engine is running. To heat up the coolant and deliver it to the radiator of the heater, the engine must reach the operating temperature. Cold air is forced through the radiator by the blower and heated up before entering the passenger compartment.

Why does it take so long to heat up the passenger compartment?

Large vehicles take longer to warm up inside than compact ones. More time is also needed to heat up both the engine and passenger compartment in sub-zero temperatures. Due to their low fuel consumption, diesel engines take longer to reach their operating temperature than petrol ones. Accordingly, the interior of diesel cars stays cold longer. The heating system of some electric vehicles doesn’t work very efficiently due to the low power of the thermoelectric heater.