Whirlpool Dryer Error AF: Restricted Airflow — Vent Blockage

1. SAFETY: Disconnect power before inspecting this appliance.
2. FIRE SAFETY: If you smell burning or see scorching on the duct, turn off the dryer immediately at the breaker and call a professional before cleaning.
3. SAFETY: Unplug the dryer (or turn off the breaker for electric; shut off the gas supply valve for gas models) before moving the machine.
4. Pull the dryer away from the wall and inspect the flexible duct section — look for kinks, crushing, or tight bends. Replace any kinked section with rigid metal duct.
5. Disconnect the flexible duct from the back of the dryer and from the wall connection.
6. Use a dryer vent cleaning brush kit (available at hardware stores) to push through the duct from both the dryer end and the wall end — rotate the brush to dislodge lint.
7. Go outside and locate the exterior vent hood. Open or remove the damper cover and clear any lint or debris from the flap and duct opening.
8. If you have a long duct run (over 25 feet), or a run with multiple bends, use a drill-powered cleaning brush or hire a duct cleaning service.
9. Remove and clean the lint screen under running water with a soft brush to clear any residue from dryer sheets.
10. Reconnect all duct sections. Verify no bends are tighter than 45 degrees and the total duct length is within the manufacturer's maximum (typically 25–35 feet for a straight run; subtract 5 feet for each 90-degree elbow).
11. Plug the dryer back in and run a timed dry cycle — AF should clear once airflow is restored.

Error AF on your Whirlpool dryer means: The dryer's airflow sensor has detected that exhaust air cannot move through the vent system at the required rate. The vent is partially or fully blocked. Unlike some dryer error codes, AF does not stop the dryer — the machine continues running, but efficiency drops and heat builds up inside the drum. Clean the vent promptly: restricted airflow is one of the leading causes of residential dryer fires in the United States. Also displayed as F4E3, F4 E3 on some models.

The most frequent cause is lint accumulation inside the exhaust duct — lint builds up in the duct walls and bends over months of use, gradually choking airflow. Work through the causes and fix steps below in order before calling a technician.

Error AF is DIY-safe. Follow all steps in sequence.

Dryer vent fires are caused by lint accumulation — the same condition that triggers AF. The U.S. Fire Administration recommends cleaning the dryer vent at least once per year. Replacing flexible foil duct with rigid metal duct is the single most effective long-term prevention step: rigid duct accumulates far less lint and does not sag or kink.

• Lint accumulation inside the exhaust duct — lint builds up in the duct walls and bends over months of use, gradually choking airflow
• Crushed or kinked flexible duct — the accordion-style duct behind the dryer is easily pinched when the machine is pushed against the wall
• Lint screen not cleaned before the current load — a fully clogged screen alone can trigger AF
• Exterior vent hood damper stuck closed or clogged with lint, preventing exhaust from exiting outside
• Duct run too long or with too many 90-degree bends — exceeding the manufacturer's maximum duct length reduces airflow below the required threshold

• Do not continue running the dryer if you smell burning — turn it off at the breaker immediately
• Do not use flexible foil duct (the shiny accordion type) for the main duct run — it sags, kinks, and collects lint far faster than rigid metal duct
• Do not vent the dryer indoors or into a crawl space — indoor venting is a fire and mold hazard
• Do not ignore AF as a minor nuisance — blocked dryer vents cause approximately 2,900 home fires annually in the US

AF returns within a few weeks of a thorough duct cleaning — the duct layout may have excessive length or too many bends

• You smell burning or see discoloration on the duct or rear panel of the dryer
• The duct passes through walls or ceilings and cannot be cleaned from either end with a brush kit

• Clean the lint screen before every load and deep-clean the exhaust duct at least once a year — more frequently if you dry bulky loads like towels and bedding regularly. Replace flexible foil duct with rigid or semi-rigid metal duct: it accumulates significantly less lint and is far less likely to kink