Electronic surface-mounted air conditioning controller for heating/cooling control in 2- and 4-pipe systems for hotel, residential and commercial premises. Designed to control continuous valve actuators, both normally closed and normally open. Particularly suitable for cooling ceiling control due to the possibility of dew point monitoring. To compensate for the inertia of controlled systems with chilled ceilings, the device has a temperature sensor input for connecting an external radiation sensor (optional). The external sensor can also be designed as a room sensor (optional) as an authority variant, where the controller should be inaccessible to unauthorized persons. An internal potentiometer can be used to select the use of the internal or external sensor or the use of both sensors with an adjustable weighting. Contact inputs for ECO function and OFF (frost protection).