Microwave won't heat food.

Wale Sarumi KomputerSolution

• 6993 Answers
• Posted on Nov 11, 2011

SOURCE: My microwave oven isn't heating my food.

Hello,

Investigate these three areas if your microwave won't heat

Power Diode

A diode is an electronic component that readily passes current in one direction only and blocks the flow of current in the opposing direction. If your microwave's diode has become defective, your microwave will not heat. Test the diode to determine if this is the cause of your problem. Replace it if it is defective.

Testing a diode

NOTE: Before you test your diode, make sure your microwave is unplugged, and that you discharge the microwave's capacitor.

Whether it is shorted or open, a defective diode will most likely show some sign of defect. Defective diodes will usually emit an electrical burning smell, signifying its defectiveness. Also, it may have split in two, or it may exhibit a burned crack, or possibly even a blistered spot.

A shorted diode is indicated by a loud humming noise from the high voltage transformer, and no heat produced when a cook cycle is initiated. Whereas little or no heat produced in your microwave, with an absence of a humming noise is indicative of an open diode. In either case, the diode has to be replaced.

With your microwave unplugged, and your capacitor discharged, use extreme caution to remove the lead that leads to the capacitor. You can leave the ground connection attached. The side of the diode that goes to the ground is usually marked with a dot, stripe, or arrow. Set your ohmmeter to R x 10,000 or higher. Touch the positive meter probe to the anode and the negative meter probe to the cathode to measure the resistance across the diode terminals. Remember that the cathode is on the side that goes to the ground, which is often marked by a dot, stripe, or an arrow.

A normal diode, that is a non-defective diode, will read anywhere from 50,000 to 200,000 ohms. Differences in microwave make and model account for this large range in resistance readings.

Reverse the meter probes and measure resistance while touching the positive probe to the cathode and the negative probe to the anode. Reversing the probes like this should result in a reading of infinity. Unless a bleeder resistor is present. The presence of a bleeder resistor would produce a reading of the value of the resistor.

High Voltage Capacitor

A capacitor is an electrical device which stores electricity. A defective capacitor may be why your microwave is not heating. The capacitor will have to be tested to determine if this is the cause of your problem. A defective capacitor will have to be replaced before your microwave will work again. Make sure you discharge the capacitor before you test it, though.

Magnetron

A defective magnetron is the third possible cause of why your microwave is not heating. Test your microwave's magnetron. Replace it if it is defective.

Testing a magnetron

NOTE: Before you test this component, make sure your microwave is unplugged, and that you have discharged the capacitor.

There are two tests to conduct in order to determine whether or not a magnetron has become defective. If you receive results other than what are detailed below, you will have to replace your microwave's magnetron. Each test is described for you here:

TEST 1: Locate your magnetron and label each of the wires attached to it so that you know which wires are to be replaced where. Set your ohmmeter to the lowest resistance scale. Take a resistance measurement between each of the magnetron's terminals by touching each probe to one terminal each. Reverse the probes and take a second resistance measurement. Each measurement should read less than one ohm.

TEST 2: Set your ohmmeter to its highest resistance scale. Touch one of the meter's probes to a magnetron terminal. Touch the other probe to the metal magnetron housing. Take special caution to not touch the two probes together. This could result in an inaccurate reading. This test should produce a reading of infinity - indicating an open circuit.

Read the tips on the below links on how to replace your microwave oven's diode and how to discharge the capacitor.

http://www.fixya.com/support/r7088355-replace_microwave_ovens_diode

http://www.fixya.com/support/r7088317-discharge_microwave_ovens_capacitor

I hope the above is helpful.

Regards.

SOURCE: Microwave won't heat food.

My Whirlpool microwave, over the stove, stopped working when my son used it to heat his food and a heavy sound came out, like something exploded in it. When I check it, there was nothing broke. Everything works fine except that it does not heat. I will appreciate any help

Nate

SOURCE: My microwave oven isn't heating my food.

This is typical of a failed magnetron: the part which actually supplies the microwaves.

By their very nature magnetrons can fail without warning from the day of manufacture but the vast majority do last longer than the manufacturer's warranty. I have noticed a trend towards more frequent premature failure with increasingly powerful ovens.

If the magnetron has failed then there is nothing you can do to fix this as it must be replaced. It's also typically the most expensive single component in most ovens so is rarely an economic repair.

Your appliance should still be within the manufacturer's warranty so you should follow their advice regarding getting the oven repaired. If you're in the UK then you have Sale of Goods Act protection for up to six years from the purchase date and if you wish can insist that the retailer replaces the oven or refunds your money as the goods were not "of satisfactory quality".

SOURCE: My microwave oven isn't heating my food.

Small component called a diode. Open up the microwave and try to find a black (usually) component that is most often connected between the magnetron (the thing that heats the food) and the chassis of the microwave oven (ground). I used to make a fortune replacing these! Costs about 5 bucks most appliance supply stores. Make darn sure you get one of the same value.