MY central air was unhooked and moved away from the house to excavate to replace weepers. I need to hook it back up. Are there any precautions I should take?

Who unhooked it? You are really going to need a professional to hook it back up, vacuum the system, and possibly recharge. This all needs to be done correctly otherwise you risk damage to the system and lack of efficeincy. Trust me, leave this one to the pros. Good luck, hope it all goes smoothly.