My micro wave keeps blowing the thermal fuse - Kenmore 66312/66319 Microwave Oven

open and look for blow fuses

This is usually due to faulty protection switches in the door. All microwave ovens are designed so that if the unit is busy micro-waving, and you somehow manage to open the door, it will immediately blow the fuse. The switch/s may have come loose from their mountings. Be very careful, because this can be very dangerous if you don't know what you are doing. Rather let an experienced person take a look.

Maybe... Did you check the high voltage diode?... A shorted diode keeps the fuse blown... Ty

Chek the H V fuse,Diode&Magnetron

micro waves use a tube inside that generates micro waves and like a light bulb they eventually blow out. the tube is not considered replaceable and cheaper to just get new unit.

The fuse is located inside the microwave. You will need to remove the front panel to get to it. It will be located on the black power wire inside the microwave and installed inline. Make sure that the microwwave is unplugged before removing the front panel. Once you locate the fuse inside you will need to remove it and test it with a continuity tester to see if it is blown. If it is make sure you replace the fuse with the same amp rating you found. If the new fuse blows again then there is an electrical short somewhere inside the microwave.

You will have to remove the micro wave from it's mount. Once you have it down, look at the top of the micro wave. There will be a panel that you will have to move from one place (where it is now) to another. This panel will either be on the top of microwave or if the mounting kit has a top plate, it will be on it. The panel normally has two screws holding it in. When you remove it, you will need to re-install it so that it blocks the air flow from coming out of the front. There should already be screw holes where you are to install it. When you have it moved, re-install the micro wave.
I hope I didn't confuse you. The only reason it's not blowing out the top is because whom ever installed it didn't move the panel. All over the stove micro waves come with this movable panel so you can vent it either way you want. If you have the installation papers, it will explain this better. Good luck.

With micro waves, this could be a number of things. They are hard to diagnose using this forum but I'll try. There are three things you can check. One being the thermal fuse. On some models, when it goes bad it put some things out. with others it puts every thing out.
if it's good, check the mag tube (Magnatron). Most of the time, it will be burned on the end if it's bad. tube. The last thing would be the fuse. It is made of ceramic and is a 20amp. It looks like a old round car fuse but it's not. It's made just for micro waves. Honestly, if the thermal fuse and the round 20 amp fuse is not the problem, you may be able to replace the micro wave cheaper than replacing the parts.
Thermal fuse $28.99.
Round 20amp fuse $1.53
Transformer $100.00.
Mag tube $87.00
Capacitor $45.00
Go to www.appliancepartspro.com and enter your model number. This will pull up every part in the micro wave and their prices. Then you will ba able to decide if you want to replace the parts. With yours being one that's built-in over the stove. These cost more and are worth putting more into. If I can help any more comment back and I'll do what I can.
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The Interlock Monitor Switch is an added
safety check on the Primary and
Secondary Interlock Switches. If the
Primary and Secondary Interlock Switches
allow the oven to operate with the door
open, the Monitor Switch will blow the
fuse.

You can get more information about adjuting the interlock switch from this link

http://136.166.4.200/contents/Microwave/LMVM1935xx/LMVM1935xx_Service_Manual.pdf

sections 7-11 thru 7-12 discuss the door interlock adjustment that will cause the 20A fuse to blow if it isn't set up right. I hope this helps you...