My microwave is only 4 years old and everything works except there is NO HEAT. Is the fuse the problem?
Answer Hello Gordon,
If the fuse were bad the unit would be completely dead. In the case of the unit working except for heating, the problem is a high voltage issue. This includes the control board, the high voltage transformer, the high voltage capacitor, the high voltage diode, the magnetron high temperature cutout, and the magnetron. One or more of these can be the issue. The only way to know for sure is to open the unit, discharge the high voltage capacitor to ground, and test the individual components. According to the manufacturer, there is no definitive test for the magnetron other than testing to ensure the terminals are not shorted to ground, (chassis).
Hello. How can you tell visually, if a fuse, AP4440371 (LG #3B74133N), is blown or still good. Since the fuse is frosted, with a black stripe around it, the element inside cannot be seen. Thank you.
Answer Hello Anthony. I'm sorry to say that the only way to check a ceramic fuse is with a tester or by passing voltage through it to a known good circuit so you can see the circuit operate. Hope this was useful!
Where is the fuse located? And how do I get to it?
Answer Hello Candy. You will need to remove the outer cover off the microwave to access and replace the fuse 3B74133Q. It is located in the control section, by the magnetron, inside a fuse holder. Hope this helps.