Function of automobile air heater: An automobile air heater comprises a shell, a tubular radiator, a water chamber, a water inlet pipe, a water outlet pipe, a motor and a fan impeller installed in the shell, and is characterized in that two horizontally arranged water pipes and a radiator with a vertical water chamber are stacked in a stepped manner in the shell, a partition plate is arranged between the two radiators, and baffles are respectively arranged at the upper part of one side and the lower part of the other side of the shell to form two independent air chambers. Two motors and wind turbine wheels are installed on one side of the radiator, and there are two air outlets on the upper and lower parts of the shell, so that cold air can be blown from the wider part of the air chamber to the air outlet on the other side; The water inlet side of one radiator and the water outlet side of the other radiator are respectively provided with an upper water chamber and a lower water chamber, and the other side is provided with a water chamber, and the water chambers of the two radiators are connected in series to make the water flow into a double U-shape.