A built-in microwave oven allows you to conserve counter space. It puts the food you're cooking in it within easy reach so you can easily tend to it. Unfortunately, microwaves don't always last a long time. When it's time to replace a cabinet-mounted microwave for a newer model, it's a fairly simple process to take the old machine out and replace it with a new one. The key to making the microwave installation go smoothly is to find a new model that is the same size as the old one.
Examine the wood cabinet frame around the old microwave oven. Find the nails or screws that hold the frame place. Unscrew the screws or gently pry off the wood with a small pry bar. Set the wood aside so you can reinstall it later. Your model may not have a frame. If it doesn't, skip this step.
Unscrew the screws from the two braces on either side of the cabinet that hold the old microwave in place. Remove the old microwave from the cabinet. It's probably heavy, so you may need a helper to help you support the microwave. As the microwave comes out of the cabinet, reach behind it and unplug it from the socket. Put the microwave somewhere out of the way so you can dispose of it properly later. Pull the old braces off the cabinet after you unscrew their fasteners.
Open the new microwave. Remove the turntable if it comes out.
Slide the new microwave into the cabinet to make sure it fits. Center the microwave and then mark the location of the new braces. Use the holes along the side front of the new microwave as the guide. Pull the new microwave back out of the opening.
Drill pilot holes in the cabinet where you marked for the braces. Hold the braces in place as you attach the screws to the cabinet.
Slide the microwave back into position. Before you push it all the way into the cabinet, reach behind the microwave to plug it into the wall. Attach the screws that fasten the microwave to the mounting brace.
Reattach the wood cabinet facing with the screws you took out. If the cabinet had finishing nails, you may need to replace the nails rather than reuse them.
Replace the turntable. Turn the microwave on to see if it works to complete the installation.
Make sure the cabinet you are putting a new microwave in has the capability of holding at least 68 Kilogram, the typical weight of a built-in microwave. The cabinet should have a solid bottom to support the microwave's weight. If the cabinet facing had too much damage as you removed it, measure and cut new pieces of matching cabinet wood the exact size of the old ones. Paint or stain the pieces to match the cabinet.