My Microwave Will Not Heat My Food: 5 Common Reasons

You finally make it home after a long day of work, and you’re looking forward to reheating last night’s spaghetti in the microwave for a quick, comforting dinner. But the spaghetti spins and spins for two minutes, only to come out still cold in the middle. What gives, why is it the microwave will not heat? Here are five common reasons for a frosty microwave.

1. You Have the Wrong Settings

If you start wondering, why will my microwave not heat?, the first thing you should do is double-check your microwave settings. You may have accidentally opted for a lower power setting that isn’t strong enough for reheating the dense pasta dish you have inside the microwave. Adjust the settings to properly heat the food.

The problem could also be with the microwave wattage. If you have a 600W model but you’re trying to reheat a casserole, the microwave may just not be right for your needs. If that’s the case, it may be time to start shopping for a new microwave with a higher wattage.

2. The Door Switch Is Faulty

The door switch is a safety mechanism that turns the microwave off any time you open the door. If you shut the microwave door, turn on the appliance, and still pull out cold food, it could be that the switch is reading the door as open. That will prevent the microwave from heating your food. 

But keep in mind that if the microwave won’t turn off or it runs even when the door is open, these could also be signs of a broken door switch. You’ll need a pro to come inspect the door switches and determine if any of them need to be replaced.

3. The Diode Is Worn Out

The diode is one of the most essential parts of a microwave, because it moves the electrical current from the microwave’s power source to the magnetron. When the diode wears out, it won’t send that energy to the magnetron, which needs the electricity in order to generate microwaves to heat food.

Aside from a microwave that will not heat, a broken diode can also emit a burning smell. Because this is a high-voltage part, leave diode inspections and repairs to a trained pro to avoid risk of shock or electrocution.

4. The Magnetron Is Broken

The magnetron is responsible for converting electrical energy from the microwave’s power source into the microwaves that heat up the food. If the magnetron wears out, it can’t produce the microwaves, leaving you with food just as cold as it was when you popped it into the microwave.

Like with the diode, repairing the magnetron means working around high-voltage parts, so don’t attempt to DIY. Instead, hire an appliance repair pro to fix this part. 

Keep in mind that magnetron repairs cost around $100 to $200, which is the same as the average cost to install a new microwave. If your microwave is over 5 years old, it may be better to replace it than pay for the cost of repairing a worn magnetron.

5. The Food You’re Heating Is Low in Moisture and Fat

Microwaves work by heating water or fat molecules, so you may notice that foods with lower moisture and fat content are stuck with cold spots throughout after microwaving. Rather than microwaving these foods, try reheating them on the stove, in a toaster oven, or in a steam oven versus the microwave.

What to Do If the Microwave Will Not Heat

If your microwave will not heat, there are some steps you can take to resolve the issue. First, make sure that the food you are trying to reheat is actually suitable for the microwave, since foods with lower moisture or fat may not heat up very well in this appliance. Then, check that you are using the right microwave settings with enough power to heat your food. Finally, check the microwave wattage, which is located in the user manual or inside the door. If the wattage is too low for frequent use or larger food items, it’s time to upgrade the microwave.

Leave any part inspections or repairs to a pro, because this appliance contains high voltage in order to produce the microwaves. There is a serious shock or electrocution risk that comes with handling microwave parts, so always trust a microwave pro near you to inspect the microwave interior, diagnose the issue, and make repairs or replace the appliance as needed.