Temperature detecting device in the passenger compartment of a vehicle

An interior temperature sensor (ITS) (28) fits in a casing (18) in or on a wall (12) adjacent to a motor vehicle's interior (14) and partly borders on the vehicle's interior. A radiation sensor (30) detects the sun's radiation that causes the ITS casing to heat up. A compensating temperature sensor (36) behind the wall is thermally decoupled from the ITS.