Kenmore 665.61639100 quit working

Please post a new help request here on FixYa and include the full model number from the tag in the cooking cavity or elsewhere on the microwave, such as the door frame, controller frame, etc. and detailed symptoms and when they occur.

That's a problem on the circuit board which can be repaired simply and inexpensively.

A YouTube video showing how to remove a typical over the range control panel assembly in under 5 minutes, is here.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

This applies to several models:

"f9 model 721.63764300
Kenmore Elite 36 " over tne counter microwave is supplied by LG made by Gold Star, made in China. It's main problem is the high voltage inverter board supplyed by Sears Parts. If you get a F-9 code on your microwave display screen and the micro quits it's probably this board. Reset the machine by pulling the power plug and waiting an hour. If it is the high voltage board is at fault it will probably fail after 45 seconds of start up. This part is really hard to get at but is less than $100. A qualified technician should be able to remove and repair this item in less than hour. Some techs will quote you $300 labor, don't buy it, it should cost a $100 or less. No need to buy another microwave."

You can usually find exploded views and order parts by entering your model number at the Sears parts site.

BUT once you have the part number from the Sears site, you can often get the parts cheaper here.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

To figure out what is wrong with it, it will have to be removed from the wall, Then the top cover will have to be removed, then you can look for any swelled capacitors, burn marks on the circuit board or any shorted wires.
The power supply is most likely faulty . You can test the power with a voltmeter from power supply to main circuit board.

You probably blew out the cavity thermal fuse you'll need a technician to replace it.

Microwaves can use a lot of amps. By law all over the range micros are supposed to be put on a dedicated 20 am circuit. That means nothing else is on the circuit but the microwave.

While your plug in micros won't generate as much amperage usage as the over the range types, your business will generate a lot of usage during peak times. It would be best if you had some on a separate circuit.

Eventually, especially if all run at the same time, you are asking for trouble. At the very least you will cause damage to the micros. At the worst you can burn some out.

Consider placing two in different places in your cafeteria, and you can still put them on surge protectors. But the amount of money you will save by turning them off for the night will be negligible.

Worry more about too many amps on one circuit.

Sirwriter

Did you have a power surge? Try unplugging the unit for 10 min and plug back in to reboot the curcuit board. If letters and numbers are being displayed it usually means the board is confused or fried.....

Most likely blew internal fuse. Pull the top/side cover off and check the line fuse. It should be behind the control panel in that area.

On some models hitting popcorn will make the microwave come on for like 2-1/2 Min's.....then shut off....Maybe yours is like that...It's also on high power

My bet is that the unit overheated and the magnetron is equipped with a thermal cutout (TCO or thermal fuse) and it blew,
protecting the magnetron.

If it runs dry, it will overheat.

But a microwave can be dead for many reasons.

It may be the fuse, which is usually located on the floor of the oven behind the control panel or between the door switches.

If the fuse is good, it may be an open thermostat or thermal cutout (TCO) / thermal fuse on or near the magnetron or on top of the cavity / body of the oven.

If it goes dead for a while during or after cooking then comes back on, the magnetron is probably overheating and causing the magnetron thermostat to open.

Then when it cools, it closes the circuit and allows power through again.

When checking thermostats, if it has a hood fan thermostat, that should read open, as opposed to the others, which should read closed.

If it went dead almost immediately after pressing the Start pad, that's usually a shorted high-voltage capacitor.

If it went dead a few seconds after pressing the Start pad, that's usually a failing high-voltage transformer.

If it goes dead or blows the breaker (or GFI) when you plug it in or open or close the door, then there's a problem with a door switch or door switch mount.

If it's intermittent or random, it may be a bad connection, usually on the control board or a loose fuse holder, or even an intermittent fuse.

You should do a continuity test on the fuse while it's in the holder (with the microwave unplugged, of course) then turn the fuse by hand or take it out and put it back in, then test it again.

If you remove the fuse, then press the meter leads against the ends, it can allow internal contact to be made and make a bad fuse appear to be good.

If you or someone you know decide to look into it, we have critical safety information and disassembly information at our site, and our link is at our listing here on FixYa.

There should also be a "mini-manual" hidden inside the unit behind the control panel or hidden on the left side behind the grille, which is very helpful when troubleshooting & testing.

You can usually find helpful exploded view diagrams and order parts by entering your full model number here.

If you do end up needing to take it down from the wall, you can download GE owner's manuals and installation instructions here.

We're happy to help you and we'd appreciate your thoughtful rating of our answer.