If the compressor is coasting down (aborted start) and you re-engage the starter, it will accelerate fast enough that when the clutch engages, something will probably break due to the high inertias of the rotors. Usually the starter shaft itself will break (it has a "shaft shear section" for just this purpose, to prevent damaging the gears). However sometimes the tower shaft between the gearbox and compressor will fail first.
Either shaft can be changed in short order, but it's an expensive lesson
