Why would a vent hood run but not vent?

Common causes: a clogged grease filter, blocked duct, stuck damper, or saturated charcoal filter (ductless). The fan must run first—if the hood does not turn on at all, see Fix a range hood that will not turn on.

Can I fix a vent hood that does not vent myself?

Yes. Clean or replace the grease filter, check the damper and duct for blockage, and replace the charcoal filter on ductless hoods. Turn off power at the breaker before any repair. Call a pro if the duct is long, vents through the roof, or you cannot reach the exterior cap.

When should I call a pro for a vent hood that does not vent?

Call a professional if the duct is long (over 15 feet), vents through the roof, the exterior cap is unreachable, or you have cleaned the filter and duct and airflow is still weak. Never work on roof vents yourself—fall risk.

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Fix a vent hood that does not vent

We'll confirm the fan runs, clean the grease filter, then check the duct and damper (ducted) or charcoal filter (ductless)—or tell you when to call a pro.

Category: Troubleshooting · Home maintenance
Time: 15–45 min
Last reviewed: Mar 6, 2026

What you'll need

Hot soapy water or dishwasher (for grease filter)
Screwdriver (if vent cap has screws)
Replacement grease filter or charcoal filter (if needed)
Vent brush or vacuum (for duct cleaning, optional)

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Quick triage — pick your path

Get started

Choose the option that matches what you see. You can jump straight to that section.

Follow this guide Work through the full procedure from confirming the symptom to verifying airflow.
Clean grease filter You want to start with the most common fix—a clogged grease filter.
Ducted hood — duct and damper The grease filter is clean; you have a ducted hood and need to check the duct.
Ductless hood — charcoal filter The grease filter is clean; you have a ductless hood and need to replace the charcoal filter.
When to call a pro The duct is long, vents through the roof, or the exterior is unreachable.

Show full guide

Steps

Goal: Confirm the fan runs, clean the grease filter, then check the duct (ducted) or charcoal filter (ductless)—or call a pro.

Turn on the vent hood fan and cook something that produces steam or smoke. If the fan runs but smoke or steam lingers, the vent path is blocked.
Good: Fan runs but venting is weak—proceed to Clean grease filter.
Bad: Fan does not run at all—see Fix a range hood that will not turn on.

Clean grease filter

Goal: Remove grease buildup that blocks airflow.

Remove the grease filter from under the hood—it may slide out or have clips.
Soak it in hot soapy water or run it through the dishwasher. Scrub off grease buildup.
If the filter is bent, torn, or still clogged after cleaning, replace it with a matching part.
Good: Filter is clean and reinstalled. Proceed to Check ducted vs ductless.
Bad: Filter damaged—replace before testing.

Check ducted vs ductless

Goal: Determine whether the hood exhausts outside (ducted) or recirculates (ductless).

Check above the hood. A duct running into the wall or ceiling means ducted hood. No duct means ductless hood.
Ducted: Proceed to Ducted path.
Ductless: Proceed to Ductless path.

Ducted path

Goal: Check the damper, duct, and exterior vent cap on a ducted hood.

Turn on the fan and look up into the duct opening. The damper should open. If stuck closed, clean or gently free it.
Trace the duct from the hood to the exterior. Inspect for grease buildup, debris, or kinks. Clean with a brush or vacuum if you can access it.
Go outside and locate the vent cap. Check that it opens when the hood runs and is not blocked. Clean the cap and damper if needed.
Good: Damper opens, duct is clear, exterior cap works. See Verification.
Bad: Duct is long (over 15 feet), vents through the roof, or exterior is unreachable—call a professional. Never work on roof vents yourself.

Ductless path

Goal: Replace the charcoal filter on a ductless hood.

Remove the grease filter and locate the charcoal filter behind it.
Replace it with a matching part (check your model number). Reinstall the grease filter.
Good: New charcoal filter installed. See Verification.
Bad: Odors still strong after replacement—confirm the filter is the correct model and installed correctly.

When to get help

Call a professional if:

The duct is long (over 15 feet).
The duct vents through the roof (fall risk—do not attempt yourself).
The exterior vent cap is unreachable from the ground.
You have cleaned the filter and duct and airflow is still weak.

If the hood does not turn on at all, see Fix a range hood that will not turn on.

Verification

The fan runs and a tissue or paper towel is drawn toward the vent grille when held nearby.
For ducted hoods: strong airflow at the exterior vent cap when the fan runs.
For ductless hoods: odors are reduced when cooking.
No smoke or steam lingering in the kitchen during normal cooking.

Escalation ladder

Work from the device outward. Stop when the problem is fixed.

Confirm symptom Verify the fan runs but smoke or steam does not vent; rule out a hood that will not turn on.
Grease filter Clean or replace the grease filter—most common blockage.
Ducted — damper and duct Check the damper opens; inspect and clean the duct and exterior cap.
Ductless — charcoal filter Replace the charcoal filter when saturated.
Call a pro Long duct, roof vent, unreachable exterior, or weak airflow after cleaning—call a professional.

What to capture if you need help

Before calling support or posting for help, have these ready. It speeds everything up.

Ducted or ductless
Whether the grease filter was clogged
Whether the damper opens (ducted)
Whether the duct or exterior cap was blocked
Steps already tried

Does the fan run but smoke or steam does not vent?

Turn on the hood fan and cook something that produces steam. If the fan runs but smoke lingers, the vent path is blocked.

Turn on the hood fan. Listen for the fan and feel airflow at the vent grille. Fan runs, weak venting: proceed to check filter. Fan does not run: see Fix a range hood that will not turn on.

Yes No (fan does not run)