As a licensed electrician, I am concerned that this is over your knowledge and experience level. Best advice is to hire an electrician.

There is information missing preventing me from giving you a complete answer.

• What type of AC unit?
• what amperage is the AC circuit?
• what voltage is the AC circuit?
• is there a neutral wire?
• how is the AC unit powered? (Is there a cord and receptacle, or is it hardwired to a disconnect/switch)

My guess is you have either a 20amp 220volt or 30amp 220volt AC circuit. Unfortunately, that will not work for you. Both of those types of circuits consist of 2 hot wires and a ground wire. In order to run a 120v circuit, you need a hot wire, a neutral wire, and a ground wire. Second, if it is a 30amo circuit, it is against the electrical code to put a 20amp or 15 amp receptacle on it.

That switch will not work for what you are trying to accomplish. IF you do have the correct power, just don't use the AC. If it isn't plugged in, it is not drawing any power.