Change the motor and sell the 115v one. Cheapest, easiest and safest option. Make sure the new motor has the same rpm, [ie same number of poles], and is the same type; that is to say you need a capacitor start/run motor
NOT a split-phase type; and if you can get the same frame size it will fit in the same bolt-holes and pulley bore and use the original vee-belt.
- If it's an inline-drive: IMHO, forget it!
BTW a VFD & Transformer could cost you more than a brand new compresssor.
Alan
ps. Don't worry too much about 50 vs 60 hz in this situation; the compressor will just run a bit
slower, eg 3000 rpm instead of 3600 rpm if it's a 2-pole.
[This message has been edited by Alan Belson (edited 09-18-2006).]