I found out that it's not always the fuse that is the problem. I have a GE above counter microwave that the lighting and pad worked but the heating unit wouldn't come on. Well the first thing I did was to remove the fuse which shut everything off. so I put it back in. Then all of a sudden the fan started up. In a nut shell, I'm convince that the problem was in my door sensor. I wiggled the door and now my microwave works. So before you think that your microwave isn't worth fixing, try this trick, you just may save yourself some money!