Article taken off ehow.com
How to Clean a Microwave With Lemon Juice
When it comes to cleaning with lemon juice, it's not about the smell, it's about the citric acid. The enzymes in citric acid cut through grease and make a greener alternative to abrasive store bought cleaners. The less money spent on cleaning the better. Using a method of steam and citric acid, microwave dirt doesn't stand a chance. And I suppose it smells good too.
Has the microwave been working overtime this past weekend? Give it a good clean with lemon juice.
Open the microwave door and remove excess debris using a damp cloth.
Set cut lemon wedges into a microwave safe bowl of water. 2 to 3 cups of water should be sufficient and 2 to 3 tbsp. of lemon juice is a simple alternative if fresh whole lemons are not available.
Place bowl in microwave oven for about 2 to 3 minutes or however long it takes to boil water in your microwave. This creates the lemon soaked steam that will cut the grease.
Let bowl stand in microwave for at least 10 minutes. The water will be very hot and by letting it stand, there is time for steam to build up inside microwave oven.
Remove bowl carefully from microwave. Set aside.
Wipe the inside of the microwave with a warm damp cloth or rag. This will remove the surface grease.
Repeat steps 2 to 6 for any remaining built up dirt and grease. The microwave walls should be squeaky to the touch when completely clean.