56MaintenanceClean, using a blast of compressed air, or replace the fresh air intake filters periodically.Connection to fresh air intakeThe unit can be made ready for the intake of fresh air through an optional filter.The optional module for the fresh air intake, containing the filter cartridge, must be applied on the left side of the unit duringthe installation phase and correspond to the holes which introduce the air into the fan compartment.During the installation phase connect a flexible circular duct, with a diameter equal to 80mm, to the nozzle which introducesthe air into the fan compartment and secure the duct to the nozzle with a fixing clamp.The length of ducting between the air conditioner and the external air intake must be as short and straight as possible.If the length of ducting is more than 6-8 metres, the use of an optional module for forced ventilation to be mounted in line isrecommended.To replace the fresh air filter:1- slide the protection cover of the fresh air module upwards.2- remove the filter cartridge.3- insert the new cartridge and reposition the protection cover.