Your hood is roaring and the kitchen is still full of smoke. Before you assume the motor died, know this: on a Broan, Best, Zephyr, or the hood built into a Whirlpool or GE over-the-range microwave, the number-one cause is a filter packed solid with grease. Work the list from cheapest to messiest and you’ll usually land on it fast.
First, pull the grease filter
Slide the mesh filter out and look at it against the light. Dark, tacky, or dripping means it’s done its job and then some. A loaded filter chokes airflow so badly the blower spins hard and moves almost nothing.
Metal mesh cleans up: soak it 20 minutes in hot water with a squirt of dish soap, scrub, dry, reinstall. A hot dishwasher cycle works too. Charcoal filters on ductless recirculating hoods don’t clean, they get replaced, and they’re cheap. Run the hood again after. If the smoke clears, you’re done and the fix cost you nothing.
Is the blower actually moving air?
Still nothing? Look at the fan wheel through the filter opening. A squirrel-cage blower caked in grease sounds normal while it pushes barely any air. Cleaning the wheel itself means pulling the assembly and killing power at the breaker, which is where the DIY part stops.
Past buildup, blowers fail two ways. A hum with no spin points at a dead run capacitor or a wheel seized in hardened grease. Dead silence when you hit the switch points the other direction: a tripped breaker, a burned speed switch, or an open winding. Sorting which one takes a meter and knowing what the reading means. Reconnecting live wiring on a guess is a real hazard, so that’s the handoff point.
Downstream: damper and duct
Filter clean and the fan clearly spinning? The problem is past the blower.
Every vented hood dumps into a duct that ends at a wall or roof cap, and that cap has a backdraft damper: a light flap that closes when the hood’s off. Grease and corrosion glue these shut. The cap is usually reachable from outside. If the flap won’t move by hand, work it loose and hit the hinge with degreaser. A corroded-through cap is a cheap hardware-store part.
Grease inside the duct run is the ugly one. It builds slowly over years and it’s flammable. Real duct cleaning means opening sections and doing it right. And check for bird nests in the cap, especially if the screen’s torn. That happens more than people think.
What’s worth doing yourself, what isn’t
Washing the filter and freeing a stuck damper are the two things worth your Saturday. Everything past that, blower diagnosis, wheel cleaning, capacitor work, duct cleaning, means disassembly or live wiring. Done wrong it either doesn’t fix the hood or creates a new problem.
Bay Area Appliance Repair Service can run motor draw, speed-switch function, and the full duct in about an hour. We track down the right blower for your exact hood, which is the slow part of any motor swap. Book anywhere across the Bay Area and we’ll get you on the schedule fast, often same or next day. The $75 diagnostic is credited to the repair once you approve it.