Generally, cars radiate heat to the compartment by recovering engine coolant, and at the same time, there are resistance wires to assist heating.
The engine itself will generate a lot of heat during operation. In order to ensure the effective work of all components, the radiator needs to be cooled by coolant. The radiator is located in the air intake grille, where there is a fan. Heating only changes the circulation route of coolant, and hot water is exiled to the radiator in the cab to control heat dissipation through valves.