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A built-in microwave set in a tall wood cabinet in a US home kitchen, its side-hinged door open with a glass measuring cup of water on the glass turntable, a flashlight and a notepad on the counter below the microwave, the display blank.

Troubleshooting

Microwave checks before booking: breaker, locks, a cup of water and the door

Microwave troubleshooting before a booking covers the breaker and outlet, a thirty-second power reset, control locks and demo modes, a thermal shutoff that clears after about half an hour, a one-minute cup-of-water heat check, and a look at the door for bends or broken hinges. Everything past that, inside the cabinet, belongs to a technician.

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  • Checks you can make at the door
  • 5-minute read
  • Across every type and make

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At a
glance.

Useful microwave troubleshooting takes about fifteen minutes, needs a glass measuring cup and a flashlight, and never goes further than the door, the controls and the circuit panel. That is enough to clear the problems that are not problems and to hand a technician a clear account of the ones that are.

Read the whole guide

Power reset30 seconds off at the plug or breaker

GE's step for a touchpad that will not respond.

After an overheat shutdownWait about 30 minutes

GE: if power does not return by then, there is a problem.

Normal door playUp to about 1/8 inch

GE says some movement does not mean energy is escaping.

Where owners stopThe outer cabinet

A capacitor inside stays charged after unplugging.

Start at the circuit panel and work toward the plug

A microwave that shows nothing and answers no key is more often starved of power than broken. Where the plug is depends on the type: a hood combination is usually plugged into an outlet inside the cabinet above it, a built-in or a drawer is often wired so that only the breaker can switch it off, and a countertop model plugs into the backsplash.

The breaker or fuse

Sharp's service checklist starts here: reset a tripped breaker or replace a blown house fuse. A tripped handle rests partway, neither on nor off; snap it all the way to off first, then back to on. If it drops again as soon as the microwave starts, stop resetting it: a second trip points to a short or an overloaded circuit, and that is worth a visit.

The outlet itself

Where you can reach the outlet, GE suggests plugging in a lamp or night light to prove it is live. Check that the microwave's plug is pushed fully home, and that it goes into a grounded three-prong outlet with no extension cord or adapter in between.

A thirty-second reset

For a touchpad that ignores you, GE recommends unplugging the microwave or turning off its breaker for 30 seconds, then restoring power and entering the cook time again. It clears a control that has hung partway through a program, which happens more than you would think after a storm or a flicker.

Rule out a lock or a showroom mode

Controls carry settings that look like a breakdown to anyone who did not switch them on. A control lock makes every key seem dead; on Sharp's drawer it is set and released by holding Stop/Clear for three seconds, and the display reads LOCK ON while it is active. A demonstration mode lights the display and counts down without heating. GE also notes that some of its controls expect the clock to be set, and that a half-entered program such as a delayed start can leave the pad unresponsive.

Our guide to reading the display goes through each of these in more detail. The short version: press Clear or Stop twice, look for a lock symbol or the word LOCK, and try the three-second hold before assuming the touchpad has failed.

Source: GE Appliances — Microwave: touch control panel not operating correctly — Use a grounded three-prong outlet; make sure the clock is set; an unfinished program such as delay start can make the pad unresponsive; unplug or switch off the breaker for 30 seconds, then reprogram; a dead unit may mean a blown fuse or tripped breaker; Sharp — Microwave Drawer SMD2470AS / SMD3070AS operation manual — Before calling for service check the cord, the house fuse or breaker, and demo mode; control lock is set and released by holding Stop/Clear for 3 seconds; always have food in the unit when it is on; do not operate with a bent door, broken or loose hinges and latches, or damaged seals

Close on an open household breaker panel with blank labels, one switch in the off position.
Close on an open household breaker panel with blank labels, one switch in the off position.

When it quits halfway through cooking

A microwave that shuts itself off during a long cycle may have protected itself from overheating. GE describes exactly this: long cooking times or blocked vents around the case can trip it, and if you then wait about 30 minutes, power may return on its own. If it does not, there is a real problem.

Look at where the unit breathes before you blame a part. A countertop model shoved against the wall or with a bread box on top, a built-in with its trim vents covered, or a hood combination whose grease filters are matted shut all run hotter than they should.

  • Shut off after a long cycle, came back after half an hour: clear the vents and use shorter runs.
  • Shut off after a short cycle, came back: note it, and book if it repeats.
  • Shut off and did not come back: book a visit.

Source: GE Appliances — Microwave: power is off — Check the breaker and prove the outlet with a lamp; long cooking or blocked vents can overheat the microwave and shut it off; wait about 30 minutes, and if power does not return there is a problem

A one-minute heat check with water

Put a cup of cold water in a glass measuring cup, run it for one minute on full power, and feel it. Clearly warm water means the heating side is working and any complaint is about settings, loading or the food. Water no warmer than when it went in points to the high-voltage side.

Never run the check with the cavity empty. GE warns that operating a microwave with nothing inside can damage the interior, and Sharp tells owners to always have food in the unit when it is on, so the energy has something to go into.

Source: Sharp — Microwave Drawer SMD2470AS / SMD3070AS operation manual — Before calling for service check the cord, the house fuse or breaker, and demo mode; control lock is set and released by holding Stop/Clear for 3 seconds; always have food in the unit when it is on; do not operate with a bent door, broken or loose hinges and latches, or damaged seals; GE Appliances — Microwave: arcing or making sounds — Operating the microwave empty can damage the interior

Look at the door, but leave the inside alone

Sharp's safety instructions list what must not be damaged before the unit is used: the door (bent), the hinges and latches (broken or loose), and the door seals and sealing surfaces. The FDA adds that a microwave whose door does not close firmly, or is bent, warped or otherwise damaged, should not be operated. Look along the edge in good light and close it slowly.

Some movement is normal. GE says a microwave door can move up and down or in and out by around an eighth of an inch, that steam around the door and moisture between the door panels after cooking are expected, and that none of this means energy is leaking. A door that springs open, a latch that does not click, or a unit that runs with the door open is different, and ends the checks right there.

  • Door closes and latches with a click, moves slightly in its frame: normal.
  • Steam at the edges or mist between the door panels after cooking: normal.
  • Bent corner, cracked window, loose hinge or no click: stop using it and book.

Source: Sharp — Microwave Drawer SMD2470AS / SMD3070AS operation manual — Before calling for service check the cord, the house fuse or breaker, and demo mode; control lock is set and released by holding Stop/Clear for 3 seconds; always have food in the unit when it is on; do not operate with a bent door, broken or loose hinges and latches, or damaged seals; GE Appliances — Microwave: normal operational characteristics — Door movement up to around 1/8 inch, steam around the door and moisture between the door panels are normal and do not mean microwave energy is leaking; FDA — Microwave ovens — Do not operate a microwave oven if the door does not close firmly or is bent, warped or otherwise damaged

What to write down before you call

A few notes make the first visit shorter. Photograph the model and serial plate, write down exactly what the display shows, including any letters or numbers that flash, and describe the sound: a hum, a buzz, a click, silence. Note whether the light, fan and turntable run, what the water check showed, and whether the trouble started after a power cut, a spill or a sparking incident.

Step
by step.

Five steps, in the order worth doing them.

01

Check the breaker and outlet

Reset a tripped breaker once, and prove a reachable outlet is live with a lamp.

02

Reset the control

Power off for 30 seconds, restore, and program a short cook time.

03

Clear locks and modes

Hold Stop or Clear for three seconds, and look for a demo or lock message.

04

Run the water check

One cup of water, one minute on full power, then feel whether it warmed.

05

Inspect the door and take notes

Look for bends, loose hinges or a latch that will not catch, then photograph the model plate.

A family warming plates of food at a built-in microwave in a bright kitchen
For the heart of your home.

Questions
owners ask.

Can I replace the internal fuse myself if the microwave is completely dead?
No. The fuse sits inside the cabinet next to the high-voltage parts, and a blown one usually means something else failed first. A technician discharges the capacitor, replaces the fuse and finds the cause.
The microwave is plugged in behind the cabinet above it. How do I cut power?
Use the breaker. Label that breaker once you have found it, so the next time anyone needs to switch off a hood combination they are not guessing in a hurry.
How long should I wait after a thermal shutdown before trying again?
GE suggests about half an hour. If the microwave comes back, clear its vents and avoid long back-to-back cycles; if it does not come back at all, book a visit.
What if my microwave passes every check but still seems weak?
Note how long a cup of water takes to get hot and compare it with how it used to behave. A slow decline in heating is worth a diagnostic visit, especially on a built-in or drawer model.

The problems
behind it.

Each has a page of its own: what it usually means and the causes in the order worth checking.

All 17 problems
A stainless microwave hood combination mounted under white wall cabinets with its display completely dark and its side-hinged door with a mesh window closed, the microwave cavity unlit behind the mesh, a quiet kitchen in daylight. Problem

Microwave Won't Turn On at All

6 causes, cheapest first

 A built-in stainless microwave in a trim kit set into a kitchen cabinet, its side-hinged door with a mesh window open and a plain glass measuring cup of water standing on the glass turntable inside the microwave cavity, the cavity lamp lit, a quiet kitchen around it. Problem

Microwave Runs but Food Stays Cold

7 causes, cheapest first

 A countertop stainless microwave on a kitchen counter with its side-hinged door with a mesh window closed, a half-heated plain glass bowl of soup visible on the glass turntable inside the microwave cavity, the unit pushed tight against a tiled backsplash with no gap at the back. Problem

Microwave Shuts Off Before the Timer Ends

6 causes, cheapest first

 Close view of the membrane touchpad beside the side-hinged door with a mesh window of a stainless microwave hood combination, the keypad surface slightly bubbled and worn at a few keys with no characters printed on them, a faint film of steam on the edge of the microwave front. Problem

Microwave Touchpad Ignores Key Presses

6 causes, cheapest first

 A stainless microwave hood combination under wall cabinets seen through its closed side-hinged door with a mesh window, the microwave cavity dark and the display blank with a plain glass bowl sitting on the still turntable, a kitchen breaker panel with one switch thrown sitting out of focus in a hallway beyond. Stop using it

Microwave Trips the Breaker or Blows a Fuse

6 causes, cheapest first

When it needs
a technician.

The repairs on the right are where this guide ends when the checks do not settle it.

Microwave diagnostic visit

A visit that times a cup of water against the clock, checks the door and its switches, then tests the high-voltage section, the controls and the moving parts one at a time until a single part is named.

Microwave light and fuse repair

Restoring a dark cavity lamp, a dead cooktop light under a hood combination or a microwave that went dead with a blown fuse, after finding what blew it.

Microwave control board and touchpad repair

Tracing a dead display, keys that do not answer or a code that keeps returning to the keypad, the ribbon, the relays or the main board, and replacing only the part that failed.

Microwave door switch and latch repair

Setting the door, its latch hooks and the three interlock switches back in order, so the microwave starts when the door is shut and stops the instant it opens, and nothing else.

More in
troubleshooting.

The checks a microwave owner can make without risk, from a timed cup of water and the breaker to the door latch, the plate and its roller ring, and exactly where to stop and book.

The whole section
Checks you can make at the door

Reading the microwave display: power-cut messages, locks, demo mode and service codes

A blinking 8888, a LOCK message, a countdown that races or a dead 8 key are settings; a code about the control board is not. How to tell them apart and what to write down.

 Checks you can make at the door

Find the microwave model plate on a hood combination, built-in, drawer or countertop

Behind the door on the frame, on a side wall, on the floor behind a drawer or under a unit above the cooking surface: where the rating plate sits on each type, and how to read it.

 Guides

All 18 guides

Six sections, by what you are trying to find out.

Back to your everyday

Read it and still not sure?

Book with what you checked and the model number, and the technician starts where the guide stopped.

Schedule a repair Call (844) 393-5858
(844) 393-5858 Schedule a repair