Fan in microwave oven going out

Yes, its main purpose is to cool magnetron, although it does also the cooking chamber ventilation. So replace it asap..

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"dave" wrote in news:PeydnV2Dn7bGr_bYnZ2dnUVZ snipped-for-privacy@comcast.com:

From the FAQ: Since 30 to 50 percent of the power into a microwave oven is dissipated as heat in the Magnetron, cooling is extremely important. Always inspect the cooling fan/motor for dust and dirt and lubricate if necessary. A couple of drops of electric motor oil or 3-in-One will go a long way. If there are any belts, inspect for deterioration and replace if necessary.

The fan is critical. They rarely fail though, usually cleaning and lubricating the bearings will get you a few more years.

The fan cools the magnetron, which runs red hot under forced cooling.* It cools the transformer. It also blows the steam out so the electrics dont get wet. All these are non-optional functions. If the fan fails, switch off right away.

NT

• used to have one where you could watch it glow in use

And in a sensor microwave it purges the chamber.

Well, I have a couple of the covers off. I have the control panel off and I can see the fan. It's in the back and not accessable without removing the entire unit (it's a GE, over the stove type). I'd like to verify if the cooling fan is not turning (it's been very quiet lately). I also took off the bottom panel to reveal a small cover which I also removed revealing the stiring motor. This oven still cooks evenly so I guess the stirer is Ok? Can I run the oven to check the fan with the control panel off? Is that safe? I can see the magnetron housing in front of the fan. It seems to be ducted under the bottom to the stirer.

Dave

I just took a chance and started the oven for 2 seconds with the panel off. The fan looks like it's turning just fine. Maybe it is the stirer.

DaveL

Well, I tried another test. I taped a piece of tissue paper to the air inlet into the cooking area and ran the unit. The airflow is simultaneous with the fan noise (which has been slow to activate and not as loud). So it is the fan and I need to lube it and the unit must come off the wall to do it. Bummer.

DaveL

Please note that if you can see the microwave stirrer through a hole without intervening wire mesh and the hole is more than a fraction of an inch in diameter, the microwaves can get to you!

However, if it was only on for a couple of seconds, the magnetron filament hasn't had a chance to get hot.

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Important: Anyth> Well, I tried another test. I taped a piece of tissue paper to the air inlet

Yes. I put the cover back on the stirrer motor before starting. I've come to the conclusion that the cooling/ventilation fan is getting weak. It's slow to start up and even then only runs at half speed. It is located towards the back so I''ll have to pull the unit off the wall to get to it. It will take me a few days to do that. I saw a thermistor on the magnetron. Looks like part of a thermal cutout circuit. Since that will keep it from overheating I think I'm safe using the oven like this for the short term. Hey, I'm a bachelor. I can't survive without my microwave!

DaveL

I would clean the bearings with a solvent (like kerosene), soak that out with paper towels getting them as clean and dust free as I can, then use a good oil for self lubricating bearings.

However that is my choice - YMMV.

Some basic clues re safety would be good for the op too, might help him live longer.

NT

That would probably work for awhile, perhaps years, but I wonder given the difficulty and time required to get to the motor if simply replacing it would be a better option.

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I'm assuming that anyone who attempts this is cheap enough to spend the time and brave enough to open the box.

Usually it's only 4 screws to remove the entire unit on those over range ones. You'll spend a lot less time removing the whole thing to work on it than you will trying to work around it.

While you do the cleaning and lubrication, check also the connections to make sure that there aren't bad contacts.

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