More info plz?

Originally Posted by JValdes
Simply start/energize the compressor with the one coil lead disconnected. Measure the voltage across the loose lead and the one still connected. If it's 240, find a neutral (if possible) in the circuit and connect it to one side of the coil. Then take one of the single wires left and reatach it. Let the neutral run through the overload relay. Tape up the remaining lead. Now you have 120 volt control for the coil. No need for XFMR unless there is no neutral available.
Or the easiest way is just to get the correct voltage coil for the starter.

ps....I bet you can find a neutral somewhere. Even if you have to pull it into the existing conduit.
Start switch and presure switch in series!!! Unless you want it to start automatically.
Check on the overload for single phase operation. Sometimes you must put in a jumper or the overload relay will not work. Look at the nameplate/paper tag.