How to Exchange a Hood With an Undermount Microwave

Turn off the circuit breaker controlling the hood. In most cases, the circuit breaker labeled "Kitchen" or "Kitchen special" delivers power to the hood.

Open the hood's electrical compartment, using the correct screwdriver to turn the compartment lid's mounting screw counterclockwise. Usually the electrical compartment's L-shaped lid mounts against the side of the hood's fan motor. The kitchen's electrical-supply wire set connects to the hood's wires inside of the electrical compartment. The electrical-supply wire set contains a black insulated wire, a white insulated wire and an uninsulated wire.

Remove the wire nuts holding the electrical-supply wire set's insulated wires against the hood's wires. Turning the wire nuts counterclockwise releases the wire connections.

Loosen the green-colored screw holding the electrical-supply wire set's uninsulated wire against the hood's housing, using the correct screwdriver to turn the green screw counterclockwise one full turn. Pull the uninsulated wire off the green screw.

Open the cabinet door above the hood and disconnect the hood's ventilation duct connection, if equipped. The ventilation duct usually taps into the top of the hood and uses metal-backed duct tape as a sealant. Peel the metal-backed duct tape off the duct connection and lift the duct off the hood's duct fitting. The ventilation duct slides over the top of the hood's duct fitting.

Remove the hood's mounting screws, using the correct screwdriver to turn each mounting screw counterclockwise. The mounting screws, located in each corner of the hood, hold the hood against the bottom of the cabinet. Lower the hood.

Locate the studs in the wall behind the cabinet with a stud finder and place a pencil mark at the appropriate spots on the wall.

Hold the undermount microwave's mounting bracket against the wall with the bracket's U-shaped horizontal tab facing away from the wall and the top of the bracket's vertical tabs touching the bottom of the cabinet. Run a manufacturer-supplied bracket mounting screw through one of the horizontal tab's screw holes and into a wall stud, using the pencil marks on the wall as a screw placement guide and the appropriate screwdriver to turn the screw clockwise. Run additional mounting screws into each wall stud, using the same screw placement and tightening method.

Position the undermount microwave's template against the bottom of the cabinet, keeping the template's directional arrow facing the front of the cabinet. Secure the template to the cabinet with masking tape.

Drill a hole through the bottom of the cabinet with an electric drill equipped with a 1/4-inch drill bit, using the template as a hole placement guide. Drill each template-identified cabinet hole, using the same method used to drill the first hole. Many undermount microwaves require four holes in the cabinet. Remove the template.

Twist the undermount microwave's black-colored wire strand around the electrical-supply wire set's black insulated wire. Combine the microwave's white-colored wire strand with the electrical-supply wire set's white insulated wire. Spin the microwave's green-colored wire around the electrical-supply wire set's uninsulated wire. Lock each pair of wires together with a wire nut -- each wire nut holds one wire from the microwave and one wire from the electrical-supply wire set.

Hold the undermount microwave at an angle against the wall below the cabinet, keeping the rear of the microwave higher than the front of the microwave. Slip the slots located on the rear of the microwave over the U-shaped tab on the mounting bracket. Force the front of the microwave up until its top side touches the bottom of the cabinet.

Hold the microwave against the cabinet with one hand, using the mounting bracket for support. Drop the threaded end of one manufacturer-supplied cabinet mounting screw through one of the 1/4-inch-wide holes in the cabinet's bottom. Finger tighten the cabinet mounting screw until the screw's head rests against the cabinet. The screw's threaded end spins into one of the microwave's top mounting holes. Repeat this procedure with each cabinet mounting screw. Tighten each cabinet mounting screw, using the correct screwdriver to turn the screw one full turn clockwise.

Slide the ventilation duct over the microwave's duct fitting, if applicable. The duct fitting uses the same hole in the cabinet that the hood's duct fitting used. Cover the seam between the ventilation duct and its fitting with metal-backed duct tape.