Maintenance device for conditioning systems

A maintenance device (1) for conditioning systems comprises a recycling unit (2) connectable to a conditioning system to draw and purify a quantity of refrigerating fluid from said conditioning system, a depositing tank (3) located operationally downstream of the recycling unit (2) to receive the quantity of refrigerating fluid, and a refilling unit (4) for the conditioning system, for drawing off a preset quantity of refrigerating fluid from the tank (3) and injecting it into the conditioning system. This refilling unit (4) comprises a volumetric dosing device (22) featuring a chamber (23) of variable volume from a minimum volume to a maximum volume for sucking into the chamber (23) a quantity of refrigerating fluid substantially equal to the maximum volume of the chamber (23).