Air conditioners, unfortunately, aren't silent machines so some noises that may seem unusual are normal. All units have a minimum requirement for the amount of pipe length between the indoor unit and outdoor unit and if that has not been met at the time of installation it may cause the unit to make louder than normal or abnormal operating noises. You should also take into consideration the location of where the outdoor unit has been installed and if proper isolating mounts have been used. This will help to minimise any noise or vibration that might be transferred through the outdoor unit to the indoor unit. If you are concerned about the noises your unit is making, you can contact Fujitsu General Assist on 1300 364 484, or record the noise and send it through to fujitsuassist@fujitsugeneral.com.au.