The control board controls your microwave by sending power to the relays. When your microwave keeps working even after you press the “stop” button, this is a good sign the control board is faulty. It is possible to keep using a microwave even when this occurs, but it's not ideal – you should replace the control board.
Press the cancel/reset button to do a soft reset on your microwave. If necessary, perform a hard reset by unplugging your microwave for 30 minutes, then plug it back in.
If your microwave oven doesn't appear to shut off when the door is open, you may have a problem with the door switch. The door switches, often referred to as interlock switches, provide power to the various components of the microwave. They are designed to interrupt the power when the door is open.
Depending on the temperature inside the microwave oven after a cooking cycle ends, the cooling fan may continue to run for some time in order to cool the microwave oven. The turntable may also continue to rotate and the light may stay on during this time. This is normal.
Check the vents for any blockages and clear them away if you find any. 2️⃣Another common reason why your microwave fan won't turn off is because the fan motor is damaged or defective. If the motor is damaged, it will need to be replaced. However, if the fan motor is simply defective, it can often be repaired.
If your microwave is making noises like a Geiger counter, the sound is coming from the magnetron that produces the microwaves. The sound is normal and there's no reason to be alarmed. If your microwave makes noises when it's in standby that are somewhat loud or strange, something could be wrong with your fan run on.
It is possible for a microwave to overheat. The microwaves heat food by targeting water molecules, if there is no moisture in the food to heat, this can cause overheating.
With normal usage for an average family and good maintenance, a microwave often lasts for 7 to 8 years. If the microwave is used less frequently by a single person or a couple and is well-maintained, the lifespan can increase to up to 10 years.
In the case of OTR microwaves, our survey analysis, which is based on the depreciation of the existing microwave and the cost of a replacement, determined that a broken OTR microwave that costs $300 or less should be repaired if it's 1 to 3 years old and considered for repair if it's 4 to 6 years old.
This can happen from cooking food for an extended period of time. A thermostat fuse is designed to protect your microwave from overheating. If your thermal fuse has been activated by your microwave overheating, your microwave will stop working. Never bypass your microwave oven's fuse!
To avoid replacing yours more than about once every 10 years—which is how long most manufacturers tell us they should last—you'll want to take care of it.
The drive motor that provides the power to rotate the plate might be faulty. The magnetron might be defective, leading to an electrical humming or buzzing. The good news is that magnetron's can be replaced. The drive coupler or roller guide might be the problem, causing the rotating plate to make noise as it moves.
If it's burnt out or damaged, it can emit a high-pitched, growling or clicking sound. It's not generally dangerous to use the microwave if it starts making these noises. However, it is a warning that the magnetron is on its last legs and needs replacing as soon as possible.
Magnetron Replacement
The magnetron is the heating technology that powers your microwave. Without it, your food is as good as cold. Replacing a microwave magnetron costs between $100 and $200 on average.
If your microwave's diode has become defective, your microwave will not heat and you will hear a buzzing noise. Test the diode to determine if this is the cause of your problem. Replace it if it is defective.
Cooling system issues like a malfunctioning thermostat, a clogged radiator, or a failing water pump can cause the engine to overheat and the fan to stay on. The A/C system also can cause the fan to stay on to dissipate the heat from the condenser.
A continuously operating exhaust fan provides a way to exhaust the stale air that builds up inside a home. The fan's airflow rate is set to achieve the number of air exchanges needed for your specific home.
Installation and Labor
Most microwave installations take one to three hours. You can expect to pay $50 to $80 per hour for a basic microwave replacement. If you need contractors other than the microwave installer, it costs $40 to $100 per hour for electricians and $40 to $80 per hour for cabinet installers.