Unit turns on when door is opened(Model NNT993SF)

Bad Door switch, back feeding power to turn table motor circuit

Time to replace it , will cost more to fix then replacement,

Sounds like a bad magnatron (the part that emits microwave energy) or maybe just a bad door switch. If the door switch is bad it won't let the unit come on.

Many microwaves have similar issues. Usually, (not always) only the light is on and the fan is running, not the section that produces the microwaves. This problem can be caused by the door switches that are out of alignment or a defective control board.

Sounds like the power relay has quit. Time for a new one.

HI:
You have a faulty door switch, the unit is not supposed to come on when the door is opened only the light.This unit may require servicing as the control board may also be at fault.

This is usually caused by either a bad door switch, a loose door switch mount, or occasionally a problem on the control panel.

Even though a door switch clicks, it may still be bad inside. Its continuity must be checked.

Door switch or mount trouble can be caused by slamming the door or by opening the door while it's cooking without hitting the Stop pad first.

There are plastic mounts inside the microwave which hold the door switches and onto which the door latches lock when you close the door.

The screws on these mounts may be loose. If they get too loose, the switches will not be activated properly.

Sometimes it's a broken tab on the switch holder, allowing the switch to rotate just out of position. This tab can be hard to see, since it is under the bottom edge of the switch.

One test that sometimes helps is to gently lift up (and/or push down) on the door or handle as you try to start it. If it works or tries to work, then it's a door switch mount or door alignment issue.

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

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

There may 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.

If you only need a switch, you can order one from us for $5 postpaid.

If you think the problem is on the control panel, we repair these nationwide by mail for $39.95 postpaid in most cases.

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

William E. Miller
[email protected]
http://www.microwavedisplay.com

It is possible that the magnatron is bad but hard to say on a no heat problem without checking all components. A lot of model give 5-7 yr warranty on that part.

open the control push boton and clean it one of the boton stoct.

I would suspect either door switches or an intermittent control circuit board, either of which can be repaired. Opening the door while cooking (without first hitting the STOP pad) is the primary cause of door switch failure over time. I have a text file on my site called "doorsw.txt" which helps in diagnosing and repairing door switch problems. You can find the file via a Google search. It will help you check and replace the door switches if you or an able friend is so inclined. In some cases, the problem is a bad connection or a bad relay on the control board. That's something we see fairly often, and we repair them for only $32.50 nationwide.