I arrived at our clients home for a second opinion for items found on an inspection report. The inspector identified the downstairs unit making a “loud noise” in the attic. I proceeded into the attic and turned the unit on to cool. This unit has a variable speed blower motor and on the low stages I could not hear anything. When the unit increased its speed I could not identify any loud noise outside of the units normal operation. We also turned on the upstairs unit and could not identify any noise outside of its normal operation. Everything is testing within range and there is not a loud noise identified on either units.