Heating system for a vehicle

A heating system for a vehicle has a heating air blower for generating a heating air stream to be introduced into the interior space of a vehicle, a heater with a heat exchanger arrangement for heating the heating air stream being delivered by the heating air blower, a mixing arrangement for setting an outside air/ambient air ratio of the air to be fed to the heat exchanger arrangement, an outside temperature sensor arrangement for generating an output linked with an outside temperature, and an actuating device. The actuating device actuates the mixing arrangement for setting the outside air/ambient air ratio on the basis of an output of the outside temperature sensor arrangement.