Range Hood Weak Suction

Checks you can do safely before you call

Start with every burner off and the filters cool, since grease on a hot filter can drip and burn. Work from a stable step stool, not from the cooktop or the countertop.

1. Degrease the filters. Switch the hood off at its breaker and let it cool, then lift the filters out and soak them in hot water with a degreasing dish soap, or run them through the dishwasher if the manual allows it. Don't use oven cleaner on aluminum filters. Let them dry before you refit them.
2. Check for a charcoal filter. If your hood blows air back into the room instead of outside, it should have a charcoal filter, which sits behind the grease filters on many hoods and over the blower on others; the manual shows where yours goes. With the breaker still off, check its replacement schedule and replace it if it's overdue or missing.
3. Try it with a window open. Put the filters back, restore power at the breaker and, with the burners still off, run the hood on high and crack a nearby window. If the pull gets stronger, the kitchen needs more make-up air.
4. Watch the outside cap from the ground. With the hood on high, look at the wall cap or roof cap from the ground for the flap opening. Don't climb onto the roof or reach into the cap.
5. Look up into the hood with the power off. Switch off the hood's breaker first, then use a flashlight to look for a damper that stays shut or a heavy coat of grease on the blower. Don't reach into the blower housing.

When to call a technician

• The filters are clean and the hood still won't clear smoke.
• The fan sounds slower than it used to, or weak on every speed.
• The damper doesn't open, or you can't see whether it does.
• Grease drips from the hood or from the duct joint above it.
• You hear the fan running but feel almost no air at the filters.

If the fan doesn't start at all, see range hood fan not working instead.

What happens at the diagnostic visit

The technician runs the blower on each setting, tests the motor and, on motors that have one, the capacitor, inspects the blower wheel for grease buildup and checks whether the damper at the hood opens fully. The duct connection at the top of the hood is checked for a gap or a crushed section. If the hood itself checks out, the technician tells you the restriction is further along the duct or at the cap, so you can decide who should work on it.

The diagnostic visit is $89 for a standard residential appliance and $129 for a built-in unit or commercial equipment; a premium brand on its own doesn't make an appliance built-in. The range hood and vent hood repair page has more on the hoods we fix.

Brand and model notes

• Miele: many Miele hoods show a saturation indicator for the grease and charcoal filters. After cleaning or replacing them, reset the indicator as the manual describes, or the hood keeps flagging the filters. See Miele.
• Bosch and Thermador: many chimney and under-cabinet hoods from these brands can run ducted or recirculating, and a hood set up to recirculate needs its charcoal filter kit in place to clean the air. See Bosch and Thermador.
• Jenn-Air and Gaggenau downdrafts: a downdraft vent pulls air sideways and down across the cooktop, so it captures less from tall pots and from the burners farthest from the vent than an overhead hood does. Clean its grease filter the way the manual shows before deciding it's weak. See Jenn-Air and Gaggenau.
• Wolf: professional-style Wolf hoods with high-output blowers reach their full pull only when the kitchen has make-up air and the duct is sized for the blower. See Wolf.