Electric heater for a motor vehicle

The heater has a set of positive temperature coefficient heating elements heating airflow. A temperature sensor (31) is arranged within the heater for measuring temperature for an indirect determination of a surface temperature of the heating element based on thermal radiation and/or thermal conduction. A control device is used for detecting whether the temperature measured by the temperature sensor exceeds a predetermined temperature value. The control device reduces the heating power if the control device states that temperature exceeds the predetermined temperature value. Independent claims are also included for the following: (1) a motor car interior heating unit (2) a method for monitoring an electrical heater for a motor car.