How do car heaters actually heat the car?

[benbrand]

How do car heaters actually heat the car....And what's the reason that it takes it so long(in the winter)? Where does the heat come from?

[SamandElla]

Water flows from the engine through a radiator inside the car just as it does in a domestic system. The radiator is made up of a matrix similar to the cooling radiator under the bonnet. Air is blown through the matrix from a fan to warm the interior of the car. The colder the weather, the longer it takes for the engine to warm the water in the system.

[ianess]

In simple terms it`s a miniature central heating system where the car`s engine is the boiler and hot water is pushed through pipes to a smaller radiator, the output of which can be boosted by the blower fan.

In the winter the water is naturally colder and so takes a bit longer to heat up to normal temperature.  You used to be able to get it to warm up quicker by partially blocking off the airflow through the car`s main radiator but I`m not too sure if that is advisable these days.