A dryer that used to finish in 45 minutes and now needs two cycles has not lost heat — it has lost airflow. Drying works by moving hot air through the clothes and carrying the moisture outside, and every restriction in that path halves the machine's effectiveness while driving up the run time, the power bill, and the fire risk. Nine times out of ten this is a vent problem, and it is free to fix.
Read this first
- Unplug the dryer and shut the gas valve on gas models before opening any panel.
- Lint is highly flammable and a restricted vent is the leading cause of dryer fires — treat a slow dryer as a safety issue, not just an inconvenience.
- Never vent a dryer into a crawlspace, attic or indoor lint trap box; gas dryers vent combustion products and all dryers dump gallons of moisture.
Step by step
Water-test the lint screen
Pull the screen out, hold it under a running tap, and watch. Water should pour straight through. If it beads up and sits on the mesh, the screen is glazed with fabric softener and dryer sheet residue — an invisible film that chokes airflow badly. Scrub it with hot water, a drop of dish soap and a soft brush, then rinse and dry it. Do this every few months if you use dryer sheets.
Clean the entire vent run, not just the first few feet
Disconnect the duct from the back of the dryer and from the wall, and run a rotary vent brush through the full length. Most people clean the first metre and stop; the compacted plug is usually further along, often at an elbow or the last bend before the exterior wall. Vacuum both ends and the dryer's own outlet port. On a typical household this needs doing annually.
Check the exterior vent hood
Go outside and run the dryer while you look at the hood. The damper flap should be blown wide open with a strong warm draft. If the flap is stuck shut with lint, painted over, blocked by a bird nest, or fitted with an insect screen, airflow is being strangled at the exit. Remove any screen or mesh — those are for other appliances and they clog with lint within weeks.
Assess the duct itself
White vinyl and thin foil accordion duct crush behind the machine, sag between joists, and trap lint in every corrugation. Replace them with rigid or semi-rigid metal duct. Keep the run as short and straight as you can: the code benchmark is 25 feet maximum, and every 90-degree elbow effectively subtracts about 5 feet from that budget. A 4-inch duct is the standard — never reduce it.
Stop overloading and stop mixing fabrics
A dryer needs air to move through the load, so a drum packed to the top dries slower than two half loads. Aim to fill the drum no more than half to two-thirds. Also separate heavy items from light ones — a load of towels and t-shirts finishes when the towels finish, which means the t-shirts get overcooked for twenty minutes while the machine keeps running.
Clean the moisture sensor bars
Automatic cycles judge dryness by measuring conductivity across two metal strips inside the drum, usually just inside the door opening or on the lint screen housing. Fabric softener builds an insulating film on them, so the dryer reads the load as dry too early, or on some machines runs far too long. Wipe them with rubbing alcohol on a cloth until they are bright metal. Try a timed cycle as a comparison test — if timed dry works fine and auto dry does not, this is your answer.
Check the blower wheel and the drum seals
With the machine unplugged, get to the blower housing and inspect the wheel. Socks, coins and shredded lint end up in there and either jam it or knock it off its shaft, which drops airflow dramatically while the dryer otherwise seems normal. Check the felt seals at the front and rear of the drum too — worn seals let air bypass the clothes entirely, so heat goes out the vent without ever passing through the load.
Confirm you actually still have full heat
If airflow checks out, verify the heat. Electric dryers run the heating element on 240 volts across two breaker legs; lose one leg and the drum still tumbles on 120 volts but heat output collapses, which reads exactly like slow drying. Reset the double-pole breaker fully. On gas models, watch the igniter cycle — if the burner lights but cycles off almost immediately, a failing high-limit or cycling thermostat is cutting heat short.
What this repair costs
Doing it yourself
$0–$80
Hiring a technician
$100–$350
Prices are general estimates for typical US jobs, not quotes. What you actually pay depends on your appliance's brand and age, the part required, your region, and each shop's labour rate. The DIY figure assumes you supply the labour and buy the part yourself.
Parts you may end up buying
| Part | Install | Typical price | Typical lifespan |
|---|---|---|---|
| Thermal Fuse | easy | $5–$20 | One-time (blows when overheated) |
| Heating Element | moderate | $20–$60 | 8–15 years |
| Cycling and High-Limit Thermostats | easy | $10–$40 | 8–15 years |
| Drive Belt | moderate | $12–$45 | 8–14 years |
| Drum Rollers and Idler Pulley | moderate | $20–$70 | 7–12 years |
| Gas Igniter | moderate | $20–$65 | 6–12 years |
| Gas Valve Coil Kit | moderate | $20–$65 | 8–15 years |
| Door Switch | easy | $10–$40 | 8–15 years |
| Blower Wheel | moderate | $20–$70 | 10–15 years |
| Moisture Sensor Bars | easy | $15–$50 | 10+ years |
Still not fixed
When to call a pro
If the vent is clear end to end, the blower is intact and the machine still cannot dry a normal load in one cycle, the fault is in the heating circuit or the control — a partially open element, a drifting cycling thermostat, or a failing control board. Also call a professional if the vent run is inside a wall or ceiling cavity you cannot access; a duct cleaning service has cameras and 30-foot rods for exactly that. Gas valve work is licensed work in every state.
More dryer guides
- Dryer Not Heating — Electric and Gas, Diagnosed in Order45–120 minutes
- Dryer Squealing or Thumping — Find the Worn Part60–150 minutes
- Dryer Won't Start — Complete Diagnostic Checklist30–75 minutes
- Dryer Drum Not Turning — Belt, Pulley and Motor Checks60–150 minutes
- Dryer Shuts Off Mid-Cycle — Overheating and Sensor Faults45–120 minutes
- Dryer Smells Like Burning — Stop and Find It Before the Next Load60–120 minutes
- Dryer Trips the Breaker — Find the Fault, Not a Bigger Breaker60–120 minutes
- Dryer Getting Too Hot — Scorched, Shrunk and Damaged Loads60–120 minutes
- Dryer Tearing or Snagging Clothes — Find the Sharp Edge45–90 minutes