KitchenAid Microwave Charcoal Filter Replacement: The Part Behind the Grille

KitchenAid microwave charcoal filter replacement, and why nobody knows about it

An over-the-range microwave is two appliances in one box. Above the cooktop it is your ventilation; at eye level it is your microwave. They share a cabinet, a control panel and a power cord, and they fail independently.

The ventilation half is where the surprise lives. If your microwave is installed to recirculate — to filter the air and give it back to the kitchen rather than sending it outside — there is a charcoal filter behind the vent grille across the top of the front panel. It is consumable. It has a life. Nothing on the panel mentions it, no light comes on, and a great many of these have never been changed since the day the unit was installed.

That is why a hood can quietly stop clearing smoke while the fan still sounds exactly as healthy as it did on day one. The blower is fine. The air is going through a filter that has nothing left to give.

First: does yours recirculate, or duct outside?

This single question decides whether the rest of the page applies to you.

Look above the microwave. Round or rectangular duct leaving the top or the back of the cabinet, heading into the wall, the ceiling or the cabinet above, means the unit ducts outside. Ducted installations do not have a charcoal filter, and there is nothing here for you to buy.

Air returning into the room through the grille at the top of the front panel means it recirculates, and there is a filter behind that grille.

In houses the answer is often ducted. In apartments and condo towers across Brickell, Aventura, Hollywood and Fort Lauderdale it is very often recirculating, because the duct route through the building was never the owner's to create. Many of these units can be configured either way at installation, which is why two identical model numbers on the same street can have different answers.

Replacing it

Ten minutes, one screwdriver, and nothing inside the cabinet gets opened.

1. Unplug it. The cord runs to an outlet in the cabinet above the microwave. Pull it, or switch off the circuit.
2. Remove the vent grille. Two screws hold it, either along the top edge of the cabinet face or just inside the top of the door opening. Take both out, tilt the top of the grille toward you, then lift it clear of the tabs along its lower edge.
3. Photograph the old filter before it moves. Which way up it sat is the detail people lose, and it does have a correct orientation.
4. Slide the old one out, sometimes past a single retaining clip, and slide the new one in the same way up.
5. Write today's date on the frame with a marker. It is the only record that will ever exist of when this was done.
6. Refit the grille on its lower tabs first, tilt it back, replace both screws, and plug the unit back in.

Order the filter against the microwave's model number, which is on a plate inside the door frame. Filters that look identical are cut to different sizes, and one that is close is one that lets air bypass it.

Do not go looking inside the cabinet. The charcoal filter is reached entirely from outside, and everything behind the case is out of bounds for good reason: there is a capacitor in there that can hold a dangerous charge long after the unit has been unplugged. Nothing on this page requires opening the case, and if a job seems to, that is the point to stop.

The other filters on the same appliance

Three filters get run together constantly, and telling them apart is most of the value of this page.

• The charcoal filter, this one. Behind the top grille, recirculating installations only, replaced roughly twice a year and never washed. It handles odor.
• The grease filters underneath. The metal mesh panels on the bottom of the microwave, over the cooktop. These are washable and want doing monthly — hot water, degreasing detergent, or the dishwasher's hottest cycle. They handle grease, and a loaded one restricts airflow and makes the fan louder.
• A refrigerator's water cartridge, which shares nothing with either except the word. That is a KAD or matching EDR part on a counter, and it has its own page here.

A hood with a spent charcoal filter and clean mesh sounds normal and does not clear the room. A hood with loaded mesh sounds strained and does not clear the room. Both are cheap. Neither is a repair.

When it is not the filters

Bring us in when the filters are genuinely fresh and one of these is true.

The fan does nothing at all. On a microwave-hood combination this is not a hood repair — the blower is part of the microwave, and the suspects are the fan motor, its control, or the board.

The fan or the light will not switch off. Usually the control or a thermostat above the cooktop that is telling the unit the range is still hot.

It runs, the plate turns, and food stays cold. That is the classic microwave failure and it is a real one. The turntable, light and fan run from ordinary household power while the heating comes from a separate high-voltage circuit, so everything can look perfectly normal with no heat at all. It is not an owner repair.

The panel is dark or the buttons do nothing. Worth checking whether control lock has been switched on by accident, which happens constantly on these panels, before anything else is assumed.

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