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Cooks fine, but fan & carousel run slow and light is dim

These symptoms began just when I moved it to a new apt. When I first observed the malfunctioning behavior, I quickly turned it off for concern of danger or damage to the unit. I took it to a certified repair facility and everything tested fine. My landlord "tested" it and said it cooked a bag of popcorn in 2 minutes, so doesn't think there is a problem with the apt. wiring or the oven. He has done nothing further in spite of my insistence the problem has not been resolved. Sure enough, it does cook normally and I am using it now with the continued odd behavior. I notice that when cooking on lower settings, the light, fan, etc. come back to life normally when the power intermittently shuts off. Other appliances in the apt. (lights, fans, etc.) mimic this same behavior. Any insights would be greatly appreciated.

Posted by kecow on

  • kecow Apr 27, 2007

    Thank you kindly, MicrowaveSvc. I feel better now, but I wanted to follow up to clarify a bit. You see, I'm not too smart about such matters.

    You mentioned chronic similar symptoms being of concern. Did you mean those regarding the microwave oven operation or more in general? The microwave does act in this way every time I use it.

    What I also may have not made clear is the extent. I've noticed a slight extra power load from microwave ovens used in others' homes and in my former ones, but nothing like this. In fact, I used this same oven in two prior apartments (been moving a lot lately) and it didn't exhibit this behavior at all. One of those was within an early 1800's built home with what I'll call some interesting circuitry. In spite of it tripping a breaker now and then, the oven never once behaved as it does now.

    The oven's interior fan is probably the most noticeable oddity. It struggles to run to such a degree that I would guess it to be operating at 20% of its ?normal? capacity. Both the volume and pitch of the fan?s whirring sound are dramatically affected. Again, everything returns to normal while the oven goes into the non-powering cycle of a lower cook setting. I rarely use this, but tried it in the effort to gather clues.

    A couple of people who have witnessed the oven in operation expressed concern that at any moment, it could trip a breaker or else ?burn out? completely. That's what I first thought as well, but neither has happened.

    Don't think I am questioning your expertise. I value it! In fact, I?m using the thing with a lot less fear of personal danger. I can live with it acting oddly as long as it continues to cook and I don't risk starting to glow! I just wanted to make sure I explained the situation thoroughly. Now I may well have over-explained it . I?m really pressing the issue by adding one more thing: I considered just buying a new microwave, but figured the same thing would very possibly happen again.

    Many thanks again MicrowaveSvc, and to anyone else inclined to reply.



1 Answer

William Miller

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It sounds perfectly normal. A microwave generally draws about 13 amps or more when cooking at full power. That's a considerable amount. This current draw will actually "load down" the power line, resulting in a small but measurable drop in the voltage. The decreased voltage means the light will be dimmer and the motors for the fan and turntable will run a bit slower. BUT if you ever have _chronic_ flickering, dimming or brightening lights in your home, it could be the result of a bad connection on the neutral, etc., which can lead to a very dangerous condition. Once in a while is okay, but if it happens a lot, your landlord or electric company should examine the lines.

Posted on Apr 25, 2007

  • William Miller
    William Miller Apr 27, 2007

    There's only so much anyone can do remotely, and I do not want to give you a false sense of security nor do I want you to take any chances where electricity is concerned.

    At this point, I would suggest trying the microwave in different outlets around the home, as long as each outlet is rated at 15 amps or better and does not have a high-current device (such as a fridge, freezer or AC, etc.) attached AND running during the test.

    If it still acts up, it may be a general power issue in the home or a problem with the microwave itself.

    If it does NOT act up in other outlets, then I would suspect the first outlet, or the power line or breaker attached to that first outlet.

    Circuit breakers can indeed go bad, especially if they have been tripped a few times. That could have happened to previous tenants. They do lose some of their metallic "temper" and their electrical characteristics can change with overcurrent, so they may not conduct as well.

    You'd have to ask an electrican, but I would assume there's something in the code that says a breaker should be replaced if it has tripped X number of times.

    Also, you might check again with your landlord to see if he will do a genuine test of the outlet and supply. If not, ask him to send out an electrician.

    If you are still genuinely concerned and feel that the problem is in the home's outlet or wiring and that your landlord has not taken your concerns seriously - or adequately checked them out - you might consider calmly asking him who you should contact next - the Fire Marshal or the State Attorney General.

    That should get his attention and make him more responsive!

    If the testing in other outlets mentioned above is not conclusive, there are 2 tests that need to be made:

    1. A certification test to measure the output power of the microwave to see if it's within its rating. The procedure is laid out here:

    2. An electrical test to measure the microwave's current consumption and the amount of voltage drop on the power line at the outlet when the oven is running at full power.

    # # #

    On a separate note, when I was expressing concern before about possible chronic symptoms, I was referring more to such problems in wide areas of the home, not just the microwave, but here's the bottom line on that other subject:

    "if you ever have _chronic_ flickering, dimming or brightening lights in your home, it could be the result of a bad connection on the neutral, etc., which can lead to a very dangerous condition."

    Good luck and be safe!



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