The most common reason for power outages in places other than California, which has extended outages during fire season as a protective measure, is a lightning strike. When that happens, a large power surge usually precedes the outage. Even though it's momentary and stops as soon as the power goes out, a lightning surge can overload appliances plugged into wall receptacles, so if your microwave won't work after a power outage, it may be because a fuse has blown. If it's undamaged, it's easy to reset. If you're having trouble, there are a few things you can check.
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How to Reset a Microwave
As soon as the outage occurs, it's a good idea to unplug the microwave and leave it unplugged until the power comes back on. The reason is that another power surge often occurs at the moment power is restored, and if the microwave hasn't already been damaged, this secondary surge may do the job. Wait for about 10 seconds after the power comes back on to plug in the appliance.
You may see an error code. For example, the GE microwave power failure code is either PF or a series of 8s, according to GE Appliances. You can cancel that code by pressing the Clear button. After you do that, you'll have to reset the clock by pressing Clock, entering the time, choosing AM or PM and pressing Clock again.
If you get an error code on another microwave brand after a power failure, you can usually clear it by unplugging the microwave again and leaving it unplugged for five minutes. If the error code persists, you have to address it, so look up the code in your user manual to determine what it means.
Microwave Won't Work After Power Outage
What you shouldn't see after restoring power to your microwave is a completely blank display. That means that no power is getting to the control panel, and that's usually the sign of a blown fuse.
The most likely culprit is the ceramic fuse, which is located next to the power cord at the point where it exits the back of the appliance. The problem is less likely to be caused by the thermal fuse, which is located inside the body of the appliance and is accessed by removing the cover. This fuse is designed to blow when the temperature exceeds its limit, but high temperatures commonly accompany power surges, so it's a possibility.
When a GE, LG, Maytag, Samsung or Whirlpool microwave fuse blows, you can check it by doing a continuity test. This test involves disconnecting the fuse and touching the leads of an ohmmeter to each terminal and checking the resistance, which should be close to 0. If the resistance is high, the fuse has blown and needs to be replaced. This is a hazardous procedure even with the microwave unplugged, so get help if you're not 100 percent confident in your electrical skills.
Considering Other Problems
Before you get out your multimeter, there are a few other inspections to make:
- Flip the breaker on and off to make sure the power to the circuit is on.
- Check the outlet for power. If it's dead, a GFCI outlet connected to the circuit may have tripped.
- Make sure the door is fully closed and locked. If there's a problem with the lock mechanism, you should get an LOC or L error code.
- The microwave may have reverted to Demo mode. Consult your owner's manual for the way to switch out of this mode.
Chris Deziel is a contractor, builder and general fix-it pro who has been active in the construction trades for 40 years. He has degrees in science and humanities and years of teaching experience. An avid craftsman and musician, Deziel began writing on home improvement topics in 2010. He worked as an expert consultant with eHow Now and Pro Referral -- a Home Depot site. A DIYer by nature, Deziel regularly shares tips and tricks for a better home and garden at Hunker and Family Handyman.