I've purchased the Whirlpool Model #: WMH73L20AS microwave and the venting fan not working (well). The intake under the microwave into the filter can be barely felt, but on the top part of the microwave it's blowing out very hard. The fan is able to cycles through all of the speeds and I can hear that the fan is changing speeds but the suction under the microwave never changes. It seems like something is blocking the intake of the air. Any ideas?

some microwaves vent to the exterior. check outside for a vent. If it is a recirculating model, perhaps the filters are plugged, the vent pathway is blocked (packaging material) or a loose panel at the back so that the exhaust fan air is leaking out somewhere else. I don't know what else it could be unless the fan is loose on the motor shaft and the fan motor is running but the fan blades are not moving air.

Go inside and check all of the connections related to the fan. Check the fuses, and the fan itself.

It is possible, you have removed and checked the filters, still the intake is low even without the protective filters. The system will need to be taken apart to find the opstruction, or as you said a hole in the venting mechanism.

If you got it hot enough from your soup there is a fan switch to turn the blower on to cool the unit. Maybe next time cook that on a different burner on the stove to try to not heat up that area under the microwave.

If the oven is set up to vent outside, then the metal mesh grease filters are used, and they should be cleaned in warm soapy water whenever they look greasy or dirty.

If the oven is set up to recirculate, then the charcoal filter is used, and it must be replaced (not cleaned) every 6-12 months, depending on use.

This model does not have a separate cooling fan like most other models. It replies on the vent fan for magnetron cooling, so if the filter(s) gets too dirty, it can reduce the cooling air flow, which can allow the magnetron to overheat and be destroyed.

I would need to know a little more to help narrow down the "no heat" problem.

If the cooling fan, turntable, and inside light all come on when you press "Start" to cook, then I would ask if you here a "thump" when you press "Start."

If so, then the high voltage section is getting energized. If not, then it may be the cook relay on the control board, which I can affordably repair.

The support page for your oven is here, and it has manuals and part lists you can download.

For more free DIY and other help & advice, feel free to contact me with your full model number and FCC ID number from the tag on your oven.

William E. Miller, AS-EET
[email protected]
http://www.microwavecontrol.com
Microwave Oven Control Panel Repair Nationwide
"Recycling by repairing since 1982"

This may be caused by a weak fan, improper installation, clogged filters, blocked air ducts, or a blocked outside vent.

Assuming yours is a Whirlpool, you can download Whirlpool owner's manuals and installation instructions here.

This will help you check the mounting and setup, as well as helping you check the filters to see where the problem lies.

Please write back with your brand and model number if you yours is not Whirlpool.

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

That's what I thought.

We see (and repair) this a lot. The problem is on the control panel, which we regularly repair nationwide by mail for $39.95 postpaid in about a week.

At our Web site, you can get details of our service, plus we have a video available showing how to remove a typical over the range control panel assembly in under 5 minutes.

This light failure often occurs when a bulb goes out and the filament shorts, or when the bulbs are removed or installed without first unplugging the oven from the power line. Either can cause such a failure on the controller.

This can often also affect the exhaust fan operation, too. The lights and fan can be inoperable or stuck on too.

Feel free to contact me directly (and please remind me of your full model number) for more information & help.

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

I would suggest that you check the manual to be sure it;s set up right.

Then you need to check any filters that are in place.

You should also check behind the grille for any obstructions or dust, etc.

1. Unplug it from the outlet.
2. Remove any screws and unlatch any tabs in the vent grille.
3. Pull up and/or out to remove the grille.

Whirlpool customer service is here and you can also enter your model number on that page to download your owner's manual, installation instructions, etc..

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