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Tappan Microwave Shuts Off After a Few Seconds

The part(s) or condition(s) listed below for the symptom Microwave shuts off after a few seconds are ordered from most likely to least likely to occur. Check or test each item, starting with the items at the top of the page.

Most Frequent Causes for Microwave shuts off after a few seconds

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Cause 1Door Switch

A door switch might be failing intermittently. Check each of the door switches for signs of overheating, arcing, or burning. If you don’t see any obvious signs of failure, use a multimeter to test each switch for continuity. If any of the switches is visibly damaged or only has intermittent continuity, replace it.

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Cause 2Micro Switch

A micro switch might be failing intermittently. Check each of the micro switches for signs of overheating, arcing, or burning. If you don’t see any obvious signs of failure, use a multimeter to test each switch for continuity. If any of the switches is visibly damaged or only has intermittent continuity, replace it.

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Cause 3Main Control Board

Control boards are often misdiagnosed—before replacing the control board, first check more commonly defective parts, particularly the door switches. If all of the other components are working properly, replace the control board.

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Cause 4Touchpad and Control Panel

To determine if the touchpad and control panel are defective, try pressing each of the buttons on the control panel. If some of the buttons respond correctly while others don’t, replace the touchpad and control panel.

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Cause 5Touchpad

If the microwave runs for a few seconds and stops the touchpad might be at fault. This is not common. Generally speaking, if the microwave display is working and some of the buttons respond correctly but some don’t, the problem is with the touchpad.

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Cause 6Control Board

Control boards are often misdiagnosed—before replacing the control board, first check more commonly defective parts, particularly the door switches. If all of the other components are working properly, replace the control board.

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Cause 7High Voltage Transformer

Microwave ovens produce a very high voltage in order to power the magnetron antenna, which emits the energy that cooks the food. When a high voltage transformer fails, it will usually arc and have a burning smell. (Warning: The microwave oven can store a lethal amount of electricity in its high voltage capacitor, even after the microwave oven has been unplugged. Due to the high running voltage and the potential for electric shock, it is extremely dangerous to replace the electronic components in a microwave. Only a licensed technician should replace the high voltage transformer.)

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Cause 8Thermoprotector

If the microwave runs for a few seconds and stops the thermoprotector may have tripped. This is a safety device to prevent the microwave from overheating. It can be tested for continuity to see if it's blown.

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Cause 9Thermostat

If the microwave runs for a few seconds and stops the thermostat might be defective. Watch our video on testing thermostats.

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Cause 10Switch Holder

The microwave switch holder is the component that houses the door switches behind the control panel. If the switch holder is damaged or misaligned, the switches may not be properly engaged resulting in the microwave shutting off unexpectedly. You will need to uninstall the control panel and inspect the switch holder to confirm it is in good condition and secured properly. Replace the switch holder with a new one if necessary.

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Cause 11Cooling Fan

A cooling fan is used to prevent the magnetron from overheating. If the cooling fan is malfunctioning, the magnetron will quickly overheat and trip the limit thermostat mounted on it, resulting in the microwave shutting off unexpectedly. You should try rotating the fan blades to determine that they turn freely. If the blades do not turn freely or the fan motor tests negative for electrical continuity, the cooling fan should be replaced.

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