When a microwave does not heat up food, its one or multiple parts can be at fault. One of the most common causes of a microwave not heating or not starting is a bad capacitor. But you should have enough knowledge to check a bad microwave capacitor symptoms that I am going to share here.
Can a Microwave Capacitor Go Bad?
Yes, a microwave capacitor can go bad just like any other part of a microwave or other appliances. The capacitor is a part of the microwave and it can go bad sometime due to a variety of reasons.
The magnetron is the main part of a microwave, it generates heat waves to cook the food. The capacitor helps to provide required power supply to the magnetron. It means that the magnetron can’t function properly if the capacitor goes bad.
8 Key Symptoms of a Bad Microwave Capacitor
A bad capacitor is a common cause of a microwave not heating up food. If your microwave doesn’t start at all, it can also happen due to a faulty capacitor.
Here I provide 7 key symptoms of a bad microwave capacitor help you understand and fix the issue ASAP.
#1. Buzzing Noise:
If your microwave makes an unusual buzzing noise when cooking/heating up the food, it is a sign of a bad microwave capacitor. Make sure that the noise is not the common noise that your microwave has been making since the first day.
A bad capacitor can cause a microwave to create continuous buzzing noise that can be irritating at times. Such a noise occurs only when the microwave is cooking some food and not in the standby mode.
#2. Suddenly Stop Working:
You should use your microwave as per instructions given in its user manual. In case you operate the microwave safely still it has stopped working suddenly, there should be some problem in the microwave capacitor.
If the capacitor goes bad, the microwave can stop working suddenly and you need to check for the issue. The most common reason for a microwave suddenly stops working is a bad microwave capacitor and you have to fix it to make it work again.
#3. Does Not Heat Up Food:
It is strange that your microwave does not heat up food while its primary job is to heat up the food. If your microwave was working fine but now it is not heating up food, it must have some problem in the capacitor. A bad capacitor can be the reason for which the magnetron cannot generate heat inside the microwave.
#4. Very Slow Heating/Cooking:
A bad microwave capacitor can slow down the cooking process of a microwave by reducing the power supply. When the magnetron does not receive enough power from the capacitor, it won’t be able to generate enough heat for cooking the food.
When the intensity of heat is reduced, the microwave will cook the food very slowly. So, it will take too long to cook raw food and reheat leftovers. You should remember that the reason for reduction in heat level of a microwave can be a faulty capacitor and you must do something to fix it.
#5. Does Not Start:
The capacitor increases the amount of power to fulfill the need of power supply for the microwave oven. When there is a problem in the capacitor, it cannot send enough power and it may cause the microwave not to start at all.
#6. Main Fuse Blown Out:
The microwave oven requires consistent and steady power supply to work properly. If there is any fluctuation in power supply or voltage, it can damage the microwave. That’s why, every microwave has a main fuse to protect its important parts from damages caused by power fluctuation.
The fluctuation in power supply can cause the main fuse to blow out. Sometimes, a bad microwave capacitor is responsible for unusual power fluctuations. So, when you see the main fuse of your microwave blown out, you should know that there is something wrong with the capacitor.
#7. Overheating Exterior:
When you cook or heat up food in a microwave, its exterior (outer body) becomes warm, that’s normal. But cooking food in a microwave must not cause the microwave exterior too hot that you can’t touch it.
If your microwave body becomes very hot while using it as per its user manual, there should be some problem in its capacitor. A bad capacitor can cause unnecessary overheating of microwave exterior.
#8. High Voltage Circuit Failed:
A bad capacitor can damage the main circuit and other parts of a microwave. If you notice any power surges, short circuits, spikes or anything that has damaged the main circuit or caused it to fail, it can be because of a faulty capacitor.
When a microwave capacitor malfunctions, it cannot control the amount of power supply going to other parts. As a result, it causes short circuits and main circuit failure. If it happens with your microwave, it’s time to check the capacitor properly and repair the microwave oven.
These are the 8 key symptoms of a bad microwave capacitor that you keep in mind. You should check your microwave oven for these symptoms and if you find any, get ready to check the capacitor to know if it needs replacement or not.
How to Check a Microwave Capacitor Status/Condition
When you see one or more symptoms of a bad microwave capacitor in your microwave, you need to check the capacitor status and condition. Because you can decide for repairing or replacement of the capacitor or other parts only after checking condition of the capacitor.
The first thing is its visual condition and the second thing is its voltage condition. Here I provide an explanation about both the visual and voltage checking methods as under.
[I] Visual Condition: Check a Microwave Capacitor Condition
The visual condition of a microwave capacitor can clearly show up if it is damaged a little or completely. It is very easy but you need to be careful when you check the capacitor condition of your microwave oven.
The microwave capacitor contains a huge amount of power even after you have unplugged the microwave from wall outlet. So, you have to discharge the capacitor first and then you can inspect its visual condition.
To discharge your microwave capacitor, you need a screwdriver with rubberized handles, rubberized gloves and needle nose pliers with rubberized handles. You can also use a capacitor discharge pen in place of the screwdriver. You can learn how to discharge a microwave capacitor to properly discharge it.
After discharging your microwave capacitor, you need to inspect the capacitor from all directions. Check for any electrical burns or physical damage or liquid damage on any part of the capacitor.
Check the contact points, terminals and chassis of the capacitor to find any kind of rust or damage. If you don’t see any issue in visual condition then the microwave capacitor is in good condition from outside.
[II] Voltage Condition: Check a Microwave Capacitor with a Multimeter
The visual method is useful to find any visible damage on a microwave capacitor but it cannot show up internal malfunctioning. Therefore it is necessary to check voltage condition of your microwave capacitor with help of a Multimeter.
You can also use an Ohmmeter but a digital multimeter is a better tool to check capacitor voltage.
You should have a Phillips head screwdriver with rubberized handles, a digital multimeter and a pair of rubberized work gloves. Here I provide the step-by-step process to check a microwave capacitor voltage with a multimeter as follows.
- Wear the gloves and get the multimeter in hands.
- Set the multimeter to Ohmic mode and set the resistance at minimum 1000 Ohm = 1kΩ.
- Touch probes of multimeter to the capacitor terminals as positive to positive and negative to negative.
- The multimeter will show up voltage readings on its display, note it down.
- Thereafter the multimeter will return to Open Line (OL) or Infinity.
- Repeat step 3 to check if the multimeter display shows voltage numbers and returns to OL or Infinity again.
- If the multimeter shows up voltage readings every time and returns to OL or Infinity, the capacitor is working correctly.
- If the multimeter doesn’t show up voltage readings or shows zero or an error then the capacitor is bad.
After checking visual condition and voltage condition of a microwave capacitor, you can come to know if the capacitor works fine or it has gone bad. If the capacitor is faulty, you should not continue using it, you need to get it replaced immediately.
Is a Microwave Capacitor Repairable?
No, a microwave capacitor is not repairable. The microwave capacitor is made in a ways to function for voltage adjustable and amplification in the microwave. Sometimes, the capacitor does not function properly or gets damaged.
When your microwave capacitor is damaged physically or from inside, you think of get it repaired but it’s not possible. The only way to fix a malfunctioning capacitor is to replace it. So, a capacitor in a microwave or other appliances is not repairable.
What Can I Do If My Microwave Capacitor is Bad or Faulty?
You can replace your microwave capacitor if it is bad or faulty. It is the only way to fix the issue because the microwave capacitor is not repairable. You cannot repair the capacitor, so you have to replace it to get your microwave start working again.
If your microwave capacitor is malfunctioning or not working, you know that it needs to be replaced. If you have required knowledge and skills then replace it by yourself. In case you don’t have required skills then hire a technician to replace your microwave capacitor safely with a new capacitor.
FAQs about Symptoms of a Bad Microwave Capacitor
A bad capacitor can cause a microwave to stop working or doesn’t start at all. Here I provide some common yet necessary questions about symptoms of a bad microwave capacitor and its solution. Kindly read all FAQs and their answers carefully.
Q.1 What is the most common cause of a microwave failure?
A bad capacitor is the most common cause of a microwave failure.
Q.2 What is the use of a capacitor in a microwave?
A capacitor receives electrical power from wall outlet and stores it, then the capacitor doubles the power when sending it to the magnetron for generate enough heat to cook the food properly.
Q.3 How do I know if my microwave capacitor is bad?
You can check the visual condition and voltage condition of the capacitor to know if your microwave capacitor is bad. You will need a digital multimeter to check voltage condition of your microwave capacitor.
Q.4 What happens when a microwave capacitor goes bad?
When a microwave capacitor goes bad, the microwave makes buzzing noise or overheats its exterior or suddenly stops working or does not start or slows down heating or causes main fuse blown out or causes circuit failure.
Final Thoughts: Replace a Bad Microwave Capacitor
When a microwave capacitor goes bad, it prevents the microwave oven from functioning properly. I have explained 8 symptoms of a bad microwave capacitor and two methods to check a microwave capacitor condition.
After checking symptoms and condition of your microwave capacitor, you will be able to know if the capacitor is working correctly or has gone bad. If it is bad or faulty, you must take an immediate action to replace your microwave capacitor.
After replacing a bad microwave capacitor with a new capacitor, your microwave will start working again. At the time of replacement, make sure that the new capacitor is the same size and voltage as the old capacitor to prevent your microwave from malfunctioning or unwanted damage.