Why isn't my range hood pulling smoke?
Updated August 2026
A range hood that runs but lets smoke and steam drift past it is nearly always a grease-clogged filter and duct, or a stuck exterior damper flap that will not open. Grease is the enemy of airflow: it mats the mesh baffle, coats the duct, and gums the little cap flap outside until almost nothing gets pulled through. Degrease the filter, make sure the wall or roof cap opens freely, and confirm the hood actually vents outdoors rather than recirculating. The causes below run from the filter out to the blower.
Safety first: a grease-caked hood is a genuine fire hazard, not just a weak vent. The layer of grease on a clogged filter and duct is flammable, and a flare-up on the cooktop can ignite it and travel into the ductwork. Keep the filter degreased, and never leave a pan of oil unattended under a hood that is not pulling. If a grease fire starts, do not use water; smother it with a lid or a Class K or B extinguisher and shut off the burner. Confirm any over-the-range unit vents outdoors, not into the attic.
Causes, most likely first
| Cause | How likely | The fix | Typical cost |
|---|---|---|---|
| Grease-clogged baffle or mesh filter | Most common | Soak the metal filter in hot water and degreaser, or run it through the dishwasher until airflow returns. | Free |
| Stuck exterior damper flap | Common | The wall or roof cap flap gums shut; free it and clear leaves or a bird nest so it swings open. | $0–40 |
| Set to recirculate, not vented | Common | A ductless hood with a saturated charcoal filter just recycles air; replace the charcoal or duct it outside. | $15–40 filter |
| Long, kinked, or undersized duct | Occasional | Crushed flex duct and too many elbows throttle the airflow; reroute in smooth rigid duct. | $100–400 |
| Greasy, gummed blower wheel | Occasional | Caked grease on the fan blades kills airflow; pull and degrease the blower wheel. | $0–60 |
| Weak or failing blower motor | Occasional | The fan spins slowly or hums without moving air; replace the motor. | $80–250 |
| Hood underpowered or mounted too high | Rare | An undersized or too-tall hood cannot capture the plume; upgrade the airflow or lower the mount. | $200–600 replace |
Check these first
- Pull the metal filter and hold it to the light. If grease has closed the mesh so you cannot see through it, that alone is choking the airflow.
- Go outside and watch the wall or roof cap while the fan runs. The flap should swing open; if it stays shut, it is stuck with grease or debris.
- Confirm the hood is ducted, not recirculating. Feel for airflow at the exterior cap, and check whether a charcoal filter is installed.
- Hold a tissue up to the hood on high. If it barely clings, the fan is not moving the air it should.
- Look at the duct run for crushed flex sections or sharp kinks that strangle the flow between the hood and the outside.
Prevent it next time
Grease is the whole story here, so the prevention is degreasing on a schedule. Wash the metal baffle or mesh filter monthly, more often if you fry or wok-cook, so it never mats shut. On a ductless hood, swap the charcoal filter on its schedule, since a saturated one kills both odor control and airflow. The range hood maintenance checklist covers the duct and damper too. Skip all of it and you pay twice, in lost ventilation and the fire and repair costs of a grease-caked hood.
When to call a pro
Call a pro when a clean filter, a freed damper, and a degreased blower still leave the hood weak, which usually means a failing motor or an undersized, badly routed duct. A blower motor replacement runs $150–350 installed, and rerouting or adding rigid duct $200–600 depending on the run. If your hood was never ducted outside and vents into the attic or just recirculates, an installer can convert it, which is the real fix for a kitchen that never clears smoke no matter how clean the filter is.
Most of the causes above are maintenance problems wearing a disguise. OnOtto keeps the boring prevention on schedule so the 2 a.m. version doesn't happen.
Stop chasing symptoms, free for 30 daysFrequently asked questions
How do I clean a greasy range hood filter?
Pull the metal baffle or mesh filter out, it usually unclips or slides free, and soak it in the hottest water you can run with a squirt of dish soap or degreaser and a half cup of baking soda for 10 to 15 minutes. Scrub with a soft brush, rinse, and let it dry before reinstalling. Most dishwasher-safe aluminum filters also come clean on a hot cycle. Doing this monthly keeps the mesh open; let it cake for a year and you may need to replace the filter entirely.
Why does my range hood blow air back into the kitchen?
Two usual reasons. Either the hood is a ductless, recirculating model designed to filter and return air rather than vent outside, and its charcoal filter is spent, or a ducted hood has a stuck exterior damper so the air has nowhere to go but back. Check whether a duct actually leaves the hood and reaches an outside cap. If it does, free the damper flap; if it does not, you have a recirculating unit and need fresh charcoal, or a conversion to vent outdoors.
Is a recirculating range hood good enough?
It is better than nothing, but a vented hood is far more effective. A recirculating hood pulls air through a charcoal filter and blows it back into the room, which traps some grease and odor but does nothing for heat, steam, or combustion moisture. A ducted hood carries all of that outside. If you fry, sear, or cook on gas, ducting outdoors is worth it. If venting outside is impossible, keep the charcoal filter fresh and run the fan longer, since a clogged filter makes a recirculating hood nearly useless.