VAC may refer to:

• volts of alternating current. It is not the same as VA for volt-amperes.

Care must be taken not to connect AC motors or transformers to direct current (DC) sources, as they can be seriously damaged by doing so. This is mostly a concern when dealing with low voltages, as normal electrical outlets almost always carry AC.

The voltage number itself is most important, as a device must never be connected to a supply higher than the device is rated to handle, or with a voltage switch set incorrectly.

• the callsign for a radio station on the west coast of Canada at Comox, British Columbia, operated by the Canadian Coast Guard.
• "Valve Anti-Cheat", software by Valve Software designed to prevent players from cheating in its online games.
• Velvet Acid Christ, an Industrial musician.