Wiring an air-conditioning thermostat requires simple tools including needle-nose pliers and a screwdriver. Removing the old thermostat and mounting the new one on the wall requires a level, tape and pencil. A photo shot with a cell phone provides a wiring diagram to prevent mistakes.
Before beginning the job, the homeowner must check to see if the existing thermostat is a two-wire or three-wire unit and have an electrician install a third wire if necessary. Two-wire thermostats are available in home improvement stores but require a battery for operation.
The process begins by removing the old thermostat from the wall. Most have covers that snap free of the main unit. Once the cover is off, the screws holding the unit to the wall are accessible. Loosening the screws allows removal of the wires. To prevent the wire from falling back into the wall, the installer has the option of using masking tape to attach it to the wall or tying a loose loop so it does not fit back through the hole.
Needle-nose pliers are useful for bending wires to fit around the screws. Once the wires are in place, the installer tightens the screws so they are snug, but avoids using so much force that he strips the screws.