The present invention concerns an actuator module (1) comprising an actuating unit (3), said actuating unit comprising a solenoid (31) having a first (31′) and a second (31″) electric terminal, capable, when excited, of generating an electromagnetic field and a PTC (Positive Temperature Coefficient) resistor (32) connected in series with said second electric terminal (31) of said solenoid (31), said actuator module (1) being characterized in that said actuating unit (3) can be controlled by activation signals and protection signals, and in that it comprises a switch circuit (33, 34), connected between said first (31′) and second (31″) electric terminal, said switch circuit (33, 34) allowing the passage of current through said solenoid (31) and said PTC resistor (32) by said activation signals; and preventing the passage of current through said solenoid (31), but allowing the passage of current through said PTC resistor (32), by said protection signals.The present invention also concerns a system for locking-unlocking a door of a household appliance, such as a washing machine and a method for protecting a locking-unlocking system.