6 Reasons Your Kenmore Microwave Is Not Heating Up | SOLVED

Sometimes, it’s the small things that can annoy you. You come home from work tired and you want to heat up some food and watch a TV show but your Kenmore microwave is not heating up. Although this is extremely frustrating, the upside is that there’s probably an easy fix for this problem.

Kenmore Microwave Not Heating Up Food?

If you’re unable to heat up food in your microwave, there are several things that might be causing the problem. In the following part of the article, I’ll explain the most common reasons for a problem like this and let you know how you can fix it.

6 Reasons Kenmore Microwave Is Not Heating

There are several reasons why your microwave won’t heat your food. However, the most common causes tend to be related to damaged componentry. I will walk you through the six most likely causes and offer some guidance as to how you can diagnose the fault.

Warning: If you are in any way unsure about carrying out the troubleshooting advice below, then don’t. Call in your local technician to take a look, or you may simply decide it’s time to send your microwave for scrap and pick up a new one.

1. Worn Magnetron

The magnetron is responsible for generating heat in microwave ovens. Like every microwave component, it has an expiration date. It can usually last for at least 500 hours. In most cases, the most you can get out of the magnetron is 2,000 hours of use. This may not sound like a lot but remember that you usually use your microwave only for a short amount of time when you’re cooking or reheating food. Damaged magnets or burned terminals often lead to problems with magnetrons.

replacing microwave magnetron Kenmore Microwave Is Not Heating Up

How to Troubleshoot the Magnetron in a Kenmore Microwave

  1. Unplug your microwave and discharge the high-voltage capacitor. This is a necessary step to avoid a potential electrical shock.
  2. Disconnect the two wires from the magnetron.
  3. Use a multimeter to check the magnetron for electrical continuity by connecting its leads to the magnetron terminal.
  4. In the event that there is no continuity, you’ll need to replace the magnetron.

2. Burned Out Diode

When the microwave diode will usually be visibly damaged if it’s burned out. The best way to know whether it’s burned out in case you don’t see any damage is to test it for electrical continuity. The diode is an important component of the microwave oven because it provides the magnetron with the voltage it needs to operate.

How to Replace a Microwave Diode

  1. The diode is located close to the high-voltage capacitor, so make sure to first unplug the microwave and discharge the capacitor.
  2. Test the diode for electrical continuity with a multimeter. Test the diode for continuity in each direction.
  3. The diode is a component that converts alternating current to direct current. If it’s working properly, it will show continuity in one direction.

3. Blown Thermal Fuse

The most common reason for a blown thermal fuse is a defective high-voltage capacitor. Problems with the high-voltage capacitor happen as a result of wear and tear from normal use. In case you recently bought your microwave, then the capacitor may have been damaged during transport. This type of problem sometimes happens after a repair if the fuse doesn’t get installed correctly. Other reasons for a blown thermal fuse include faulty door switches and defective cooling fans.

Troubleshoot a Faulty Microwave Thermal Fuse

Electrical flow is not possible in the event of a blown thermal fuse. After you unplug your microwave and discharge the high-voltage capacitor, you can check the fuse for continuity. In case you have to replace the thermal fuse, the process is pretty straightforward. However, this type of issue may also be related to another faulty part of the microwave, including the door switch and the high-voltage capacitor.

4. Faulty High-Voltage Transformer

If you ever notice that the high-voltage transformer in your microwave oven is producing sparks of electricity, you should stop using it immediately. The transformer plays a crucial role in powering the magnetron, so it can be one of the more common issues for why your microwave is not working. Another way to tell if a high-voltage transformer may be faulty is if you notice a burning smell coming from the appliance.

How to Test a High-Voltage Transformer in a Microwave Oven

All you’ll need to test a high-voltage transformer are rubber gloves, a screwdriver, and a multimeter.

  1. Unplug the microwave and discharge the high-voltage capacitor.
  2. Next check both the secondary high-voltage winding and the secondary low-voltage winding.

In case you’re not sure how to do this, you can check out the video below.

5. Faulty High-Voltage Capacitor

The magnetron needs high voltage to operate. That’s where both the diode and the high-voltage capacitor come into play. The high-voltage capacitor stores a lot of electricity even when your microwave oven isn’t plugged in. That’s why you need to be very cautious and discharge the capacitor or call a repair technician for help.

How to Check a Microwave Capacitor

After unplugging your microwave oven and discharging the high-voltage capacitor, you can test the component with a digital multimeter. Before you do this, you can first check whether there is any visible damage to the capacitor. This will indicate that a replacement is needed.

If you have experience fixing appliances or at least checking components for electrical continuity, you can grab your multimeter and set it to the ohm mode. Make sure it’s set to at least 1,000 ohms and connect the probes of the multimeter to the terminals of the capacitor. In case readings show zero, you will need to replace the high-voltage capacitor in your microwave oven.

6. Faulty Door Switches

Microwave ovens are designed in a way that won’t work unless the door is closed. This is a safety mechanism made to protect humans from burns caused by microwave radiation. In case your Kenmore microwave is not heating up, it may be due to a faulty door switch.

How to Replace a Faulty Door Switch

Replacing a faulty door switch is easy and within the scope of a competent DIY enthusiast. First, you’ll need to remove it from the door panel. You’ll most likely have to remove screws mounted to the plastic frame of the microwave.

microwave door switch

Door switches for microwaves are very cheap, so your best bet is to replace them instead of trying to fix them. Simply install the new door switch the same way you removed the old one.

To find what component you need, get your microwave model number or serial number from the information panel at the back or side of the machine. You can then quote this to your component supplier to make sure you get the correct replacement part.

Microwave Making Squealing Noise and Not Heating

If in addition to not heating up you hear squealing noises coming from your microwave, it’s usually easy to identify what the exact problem is. Here’s the main reason for a problem like this.

Worn Magnetron or Diode

When squealing sounds are coming from your microwave, there’s almost certainly a problem with your magnetron. You may hear other unusual noises coming from the appliance, including a loud clicking sound. You may also notice a burning smell coming from your microwave that has nothing to do with the food you’re trying to reheat. This is a sign of a magnetron that’s overheating.

Microwave Won’t Turn or Heat

It can be pretty frustrating when your microwave won’t heat up. But if it also won’t turn, you’ll at least have a good idea of what the problem is. Here’s what usually causes a microwave to not turn or heat.

Turntable Motor Faulty

The turntable motor is a microwave component that gives the appliance its spinning force. After a while, the motor may become worn out. That’s why replacing a defective turntable motor is a common repair. If you know your way around appliances, you can check whether there is a problem with the motor using a multimeter to test it for electrical continuity. If it tests negative, you’ll need to replace it.

Fixing A Microwave That Is Not Heating

How do you fix a microwave that is not heating up? There’s definitely the option to do it yourself. I recommend the DIY approach only if you have considerable experience with fixing appliances. Otherwise, you should rely on help from a repair technician.

Is Your Microwave Still Under Warranty?

When your Kenmore microwave is not heating up, the first thing you should do is check whether it’s still under warranty. If so, there is an easy solution to the fix. You’re entitled to a free repair or replacement of your microwave. Don’t try to fix anything yourself if the appliance is still under warranty.

Cost to Fix Vs Buying A New Microwave?

Before you start thinking about repairs, take a moment to think about how long you’ve been using your microwave. In case it’s been years since you bought it, there may be issues with several parts of the appliance. In this case, buying a new one would be cheaper than repairing your microwave.

You can call a repair technician to determine how much a repair would cost. According to angi.com the average cost of microwave repairs undertaken by their tradesmen is $150, this ranges between $50-$400.

Compare the expenses to the price of a new microwave and you’ll see what the better option is. Keep in mind that if you’ve had the microwave for a long time, it’ll only be a matter of time before other components start malfunctioning so make sure you take that into account when making calculations.

Solved: Kenmore Microwave Not Heating

If your microwave is not heating up, it could be due to one or more common issues like blown thermal fuses, burned-out diodes, worn magnetrons, and faulty door switches. I always recommend calling a repair technician to fix the problem. But if you’re skilled at repairing appliances, you can try fixing it yourself. In case you have an old microwave, it might be best to buy a new one instead of spending money on repairs.

Appliance Service Technician | Website | + posts

Andy has over 8 years of experience working on residential household appliances, performing diagnostics, and repairs across most major brands. He graduated from the Denver Institute of Technology, is NASTeC certified, and has worked for Mr. Appliance. Andy has contributed to features on major publications including Better Home & Gardens, Family Handyman, and Yahoo.com.

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