A device for sanitizing a unit of an air conditioning system having a source of sanitizing fluid, means for the controlled delivery of a jet of sanitizing fluid, suctioning means to generate suction flow is provided. The device has suction opening shaped to direct the suction flow towards a determined direction with respect to the direction of the jet of sanitizing fluid. The suction opening is smaller than the unit of the air conditioning to be sanitized in order to be alternately moved from a first portion of the unit towards a second portion of the same unit.
