GE Microwave Not Heating Up? Why and How to Fix

Microwaves make it quick and easy to cook all sorts of foods, especially leftovers. But, sometimes, they can break down. Your microwave may look like nothing’s wrong (the turntable still turns, the light still goes on, and the timer still counts down) but, when you remove your food, it’s not cooked or even warm. 

Your GE Microwave may not be heating up due to a complicated electrical problem. It can be due to a defect in one of the parts, a burnt-out magnetron or capacitor, or even a blown fuse inside the microwave. You should not attempt to fix your microwave unless you are a professional.

In this article, you will find out why your GE microwave may not be heating up and how to fix it. 

Reasons Your GE Microwave Is Not Heating Up

Before you read on, it is imperative to know that even when a microwave is unplugged, it holds a lethal amount of electricity. Only professionals should tinker with such a machine.

A microwave is a complicated machine, and there are many moving parts. Thus, some of these parts sometimes break down or fail. 

Before you call someone to fix it or buy a new one, there are a few things you need to make sure you check with your microwave.

• Make sure your microwave is not on “timer.” Sometimes, you may accidentally hit the timer button on the microwave instead of the cook button. The timer is strictly a feature that acts as a way of counting down the time, not a way of cooking your food. This may be your problem.
• Make sure your door is all the way closed. If the microwave door is not fully closed, it will not work properly. Make sure the door is closed all the way, but do not slam the door shut. This may damage one of your door switches.

If you’re sure you didn’t hit the “timer” button, and the microwave is closed, then your microwave may not be heating up due to the following reasons:

• High voltage diode defect. A defective high voltage diode may be the cause of your broken microwave. A diode provides high voltage to the magnetron, thus heating the food.
• Door switch defect. A normal microwave usually has three to four door switches. If one of these is faulty, the door will not close properly, and the microwave itself will not heat up.
• Burnt-out magnetron. Using high voltage, a magnetron is the part of the microwave that heats the food. If it is burnt out, this may be the cause of your issue.
• Burnt-out capacitor. The high voltage capacitor, in conjunction with the high voltage diode, doubles the voltage output. Once you have a burnt-out capacitor, your whole high voltage circuit will stop working, causing your microwave to not work properly.
• Broken transformer. A high voltage transformer transfers energy from circuit to circuit. If yours is broken, you will probably smell a burning smell. 
• Blown thermal fuse. The purpose of the thermal fuse is to shut off the microwave if it overheats. If your microwave is not heating up, you may have blown this fuse.
• Tripped thermoprotector. Similar to the thermal fuse, the thermoprotector is there to cut off power to the microwave if it overheats. If the thermoprotector was tripped due to an overheated microwave, you might have found your reason for your faulty microwave.
• Defective main control board. Although it is rare, your main control board may have broke, and this may be causing your heating problem.

How to Fix Your GE Microwave

Now you know the most common reasons why your GE microwave is not heating up. The next step, naturally, is to try to fix the problem. But, as I mentioned above, a microwave contains a lethal amount of electricity, even when unplugged. Do not attempt to fix your microwave unless you are a licensed professional. 

If you are an electrician or a professional, here are several ways to fix the issues mentioned above:

Test Your Diode 

1. Unplug the microwave.
2. Access the diode by removing the cabinet. 
3. Discharge the high voltage capacitor.
4. Test the diode with a multimeter. The meter leads should reveal continuity in only one direction. If not, you will need a new diode. Here is a GE-compatible Universal Microwave Diode.

Test Your Door Switches

1. Unplug the microwave.
2. Access the door switches by removing the cabinet.
3. Remove each door switch.
4. Test the door switches with a multimeter. The multimeter should reveal continuity. If not, the door switches need to be replaced. Here are GE-compatible Lonye Microwave Over Door Switch Replacements.

Test Your Magnetron

1. Unplug the microwave.
2. Access the magnetron by removing the cabinet.
3. Discharge the high voltage capacitor.
4. Test the magnetron with a multimeter. The results should read 2 to 3 ohms of resistance and continuity. If the results are anything different, you need to replace your magnetron. I recommend this replacement from Amazon.com: Raven Magnetron for GE Microwaves.

Test Your Capacitor 

1. Unplug the microwave.
2. Access the capacitor by removing the cabinet.
3. Discharge the high voltage capacitor.
4. Using an ohmmeter, test the capacitor. It should have a reading of infinity. If not, you’ll need to replace the capacitor.

Replace Your Transformer

1. Unplug the microwave.
2. Access the transformer by removing the cabinet.
3. Discharge the high voltage capacitor.
4. Disconnect the six transformer wires, unscrew the mounting screws, and remove the old transformer.
5. Attach the new transformer by screwing it in with the mounting screws. Then, attach the new wires to the appropriate ports. I recommend this replacement from Amazon: GE Microwave Transformer.

Replace Your Thermal Fuse 

1. Unplug the microwave.
2. Open the microwave door and remove the screws that secure the grill in place.
3. Slide the grill to the left and remove it.
4. Lift the control panel up and forward, revealing the thermal fuse.
5. Disconnect the thermal fuse wires, unscrew the mounting screws, and remove the old thermal fuse.
6. Attach the new thermal fuse by screwing it in with mounting screws. Then, attach the new wires to the appropriate terminals. I recommend this replacement GE-compatible Microwave Ceramic Slow Blow Fuse.
7. Slide the grill to the right to put it back in place.
8. Replace the grill screws. 

Replace the Thermoprotector 

1. Unplug the microwave.
2. Uninstall the microwave and remove the cover.
3. Avoid the high voltage capacitor.
4. Remove the screws that secure the air duct assembly and move it out of the way to access the thermoprotector.
5. Disconnect the thermoprotector and remove it from the retaining tabs.
6. Attach a new thermoprotector by placing it under the retaining tabs and reconnecting the wires. I recommend this replacement GE Thermo Protector.
7. Replace the screws that secure the air duct assembly.
8. Reinstall microwave.

Replace the Main Control Board

1. Unplug the microwave.
2. Open the microwave door and remove the screws that secure the grill in place.
3. Slide the grill to the left and remove it.
4. Remove the mounting screws and grounding wire screws.
5. Detach the ribbon connector and remove the old main control board.
6. Attach the new control board by connecting the ribbon connector and replacing the screws. I recommend this GE Main Control Board as a replacement.
7. Replace the grounding wire screws and the mounting screws.
8. Slide the grill to the right to put it back in place.
9. Replace the grill screws. 

When replacing parts, always remember to match the model number.

Final Thoughts

If your GE Microwave is not heating up and cooking your food, there are many components that could be causing the issue. This article listed several of the problems that may lead to a faulty microwave. It also listed eight possible solutions to these problems. 

There is no quick-fix to resolve microwave issues. Always consult a professional electrician before doing anything with your microwave (other than cooking, of course!).

Jake Alexander

Jake is a freelance writer from Pennsylvania who enjoys writing about science and sports. When he’s not writing for Temperature Master, he can be found watching the NFL or playing basketball with his friends.