Manager said units in showroom don't seem to be keeping up. Checked all three package units on showroom. Found contactors chattering when second stage kicks in. Found transformer tap was set to 230 voltage and build is 208. Wrong transformer tap is causing too low of control voltage making contactors chatter then compressors go out on internal temp. Changed transformer taps to 208 voltage, reset units and ran them through both stages of cooling, checked charge on showroom units (both stages). Gonna need to 300 foot of water hose to clean condensing coils. There is a mop sink in backroom, so we will have to run water hose out to through the backroom then up to roof to clean them. Condensing coils are multi pass. Will need to split and clean all condensing coils. Will reschedule maintenance on units.