Why Your Microwave is Not Heating (How to Fix It) – Volt Fixer

fixing a microwave that is not heating

Why is My Microwave Not Heating?

A microwave may not be heating food due to a blown fuse or a faulty high voltage diode. Replacing these parts will often fix the problem:

  • Blown fuses
  • Faulty high voltage diode
  • Faulty door switch
  • Faulty magnetron
  • Faulty thermal Fuse
  • Faulty ceramic fuse

Before attempting to fix your microwave, confirm that there ’ s a real trouble with it heating up.

  • Check the power settings. Be sure that the microwave isn’t on the low power setting, which could cause food to not be heated as strongly. Stop the microwave, then press the power button to ensure it’s performing at 100% power.
  • Check if it’s heating consistent. To ensure that the microwave is heating consistently, fill a microwave safe glass about half full and place it in the microwave on full power for 1 minute. Repeat this process several times with fresh water each time, and if the water is not consistently warm then there is a problem with the heating.
  • Check for power failure. If your home recently had a power outage, the microwave’s settings may be interrupted. If the microwave displays “PF” (power failure) or the numbers “8888” (code that indicates microwave lost power), simply press the CLEAR button then reset the microwave’s clock.

High Voltage Diode Problem

This is the most common cause a microwave stop working, particularly if the microwave is making a buzz or humming noise without heat .
The senior high school electric potential diode helps to power the magnetron by allowing current to alone pass in one management, giving the microwave the energy, it needs to work. It may give off a burn smell if it ’ mho shorted or open .
Fixing a microwave with this issue requires opening the device up, so it is recommended to call a license technician to test and repair it .

Door Switch Problem

The doorway to the microwave contains three or four door switches that activate when the door is closed and tells the microwave that it ’ s safe to begin heating. If the microwave has power but refuses to turn on, it ’ s probably that one of the door switches is not working .
To check if this the reason why the microwave international relations and security network ’ t heat, ensure that the light inside the microwave turns off when the door is closed. If the ignite doesn ’ thyroxine go off, call a accredited technician to replace the door switches .

Magnetron Problem

If the microwave heats at a low level or heats sporadically then stops, it could besides be a problem with the magnetron. The magnetron is a key share of the microwave, as it produces the heat necessary to cook your food .
Problems with the magnetron could be caused by age, a defective switch or a botch fuse. If the magnetron ’ south fuse has blown, there would be a chain effect of failing parts throughout the device .
Call a licensed technician to repair the magnetron and switch as it involves opening the microwave.

Thermal Fuse Problem

The thermal fuse cuts off power to the microwave when it overheats. Use a multimeter to determine if the thermal fuse has been blown and test it for continuity. If the fuse doesn ’ deoxythymidine monophosphate have continuity, it has to be replaced. It can not be reset and if it ’ sulfur blow, it has to be replaced. It is recommended to call a accredited technician to replace the thermal fuse .

Microwave Repair Safety

Microwaves operate at a identical high electric potential, running up to 3400Vrms. This is 5 times more dangerous as the 1500V viewgraph line of a train because of the office proportional to the hearty of the electric potential .

Individual safety precautions:

  • Wear electrical insulating rubber gloves and boots, although this doesn’t protect against 4000V.
  • Use the correct tools and ensure that they are in good condition.
  • Refrain from wearing loose clothing and jewelry, and tie back long hair.
  • Don’t do measurements at high voltage, as high voltage passes through the insulation of the probe easily.

Microwaves are high voltage appliances and should never be taken aside when plugged in. A microwave must always be earthed, so the alloy chassis has to be connected with a separate cable with the land peg in the rampart socket .

Microwaves generate high voltages and dangerous amounts of radio frequency radiation. Attempting to repair a microwave yourself is not recommended. 

I recommend calling a accredited technician for any serious problems with a microwave, specially if it require disassembling the unit .

How to Fix a Microwave that Turns On but Stops Heating Evenly


High Voltage Diode

If your microwave turns on but doesn ’ metric ton estrus up it could be a problem with the high electric potential diode .
How to test your microwave’s high voltage diode with a multimeter:

  1. Unplug your microwave before beginning inspection.
  2. Locate and remove your high voltage diode to test it for continuity. Accessing it requires removing the cabinet and discharging the high voltage capacitor.
  3. Set the multimeter to Rx1 and touch the probes to the terminals. After that, reverse the probes to check for continuity in the other direction. A reading should show continuity in one direction, but not the other.
  4. If the diode doesn’t show continuity or shows continuity in both directions, a replacement high voltage diode is necessary.

Door Switch

When the light on the microwave doesn ’ deoxythymidine monophosphate go out after the door is closed, there may be a problem with the doorway trade. If this component doesn ’ metric ton workplace, the fan and stirrer may distillery function, making it look like the microwave is even working .
How to test your microwave’s door switch with a multimeter:

  1. Disconnect the microwave from the power source.
  2. Verify that the door hooks trigger the door switch mechanically. If they do, remove the microwave’s cabinet, locate the door switch and remove it to test for continuity.
  3. Set the multimeter to Rx1, depress the actuator button and touch the probes to the switch’s terminals. This should produce a reading of 0, indicating continuity.
  4. If the test results do not match the above, replace the door switch.


A microwave that doesn’t heat up may have problems with its magnetron.
How to test the magnetron with a multimeter :

  1. Ensure the microwave is disconnected from its power source.
  2. Remove the microwave’s cabinet to access the magnetron. Discharge the high voltage capacitor, verify that the high voltage diode is working and the mounting bolts are tight. If no other issues are found, remove the magnetron to test if. (Do not attempt to take apart the magnetron, as it contains beryllium oxide in the ceramic insulators which can be fatal if it enters the lungs)
  3. With a multimeter set to Rx1, touch the probes to the terminals. This should show a reading of 2 to 3 ohms of resistance. Then, move one probe to touch the metal housing of the magnetron. This test shouldn’t indicate that continuity is present.
  4. If the results of test do not match the above, a replacement magnetron is required.

A microwave that doesn ’ thyroxine estrus evenly could have problems with its components or it plainly be due to food with unlike ingredients have different rates of absorbing heat. besides, microwaves absorb heat into the surface more easily than the center .

How to Fix a Microwave that is Not Turning On

Door Switch

A microwave that doesn ’ thymine turn on could have issues with the door switch. The door switch signals the other parts to turn on when the doorway closes and to stop run when the door opens .
How to check door switch:

  1. Unplug the microwave and remove the cabinet.
  2. The switches have wires attached to the terminals marked common (C) and normally open (NO). Check for continuity using a multimeter.
  3. Set the multimeter to Rx1, depress the actuator button and touch the probes to the switch’s terminals. This should produce a reading of 0, indicating continuity.
  4. If the test results do not match the above, replace the door switch.

Ceramic Fuse

If the microwave doesn ’ thyroxine change by reversal on and has a blank display, there may be a trouble with the ceramic blend. The ceramic fuse is used to protect the components of the microwave in the event of a hard power fluctuation or critical mistake with a component .

How to check ceramic fuse:

  1. Ensure the microwave is unplugged from a power source before inspection.
  2. The ceramic fuse is located inside the cabinet near the entry point of the power cord. Check for continuity with a multimeter.
  3. If the fuse has failed for no apparent reason, check major components such as the magnetron, high voltage diode, capacitor and transformer, associated wire terminals before changing the fuse.
  4. If the fuse failed when opening or closing the door, check for a shorted door switch, monitor switch or improper adjustment of the door latch assembly.
  5. If an issue is found, use only manufacturer suggested part numbers when replacing the fuse.

Thermal Fuse or Cut Out

thermal fuses are to prevent the microwave from overheating. If your microwave doesn ’ t turn on, there could be a trouble with the thermal blend .

How to check thermal fuse:

  1. Disconnect the microwave from a power source.
  2. The thermal fuse is located inside of the cabinet, near the magnetron or oven cavity. Remove the cabinet and remove the wires from the terminals. Use a multimeter to check for continuity.
  3. If no continuity is found, replace the fuse.

Door Latch Assembly

A microwave that won ’ metric ton turn on may have a problem with its door latch fabrication .

How to check door latch assembly:

  1. Locate the door hooks that protrude from the door. The door hooks fit into the door latch holder by the frame of the microwave.
  2. If either of the hooks are broken or don’t have any spring tension, the switches won’t be engaged.
  3. The microwave won’t turn on if this happens and requires replacement of the assembly.