Two different complaints tend to come in under the same name. One dryer tumbles for an hour and the clothes come out as cold and wet as they went in. The other gets warm, but it takes two or three cycles to dry a load of towels. They share a lot of causes, and nearly all of them lead back to the same thing: air.
A dryer is really a heater with a fan. It pulls in room air, warms it, pushes it through the tumbling clothes to pick up moisture, and sends it outside through the vent. If that air can't leave, the dryer can't dry, and after a while it protects itself by shutting its heat off.
Safety before you start
- •Electric dryers run on 240 volts. Unplug the dryer or switch off its breaker before opening any panel.
- •Gas dryers also plug into a regular outlet for the drum, controls and igniter. Unplug the dryer and close the gas shutoff valve on the supply line before moving it.
- •If you smell gas, don't touch switches or the dryer. Leave the house and call your gas utility from outside.
- •Never run a gas dryer with the vent disconnected. The exhaust contains carbon monoxide.
The vent is the first suspect
In an older house, the dryer often sits in the basement and the vent can travel a long way before it reaches the outdoors: across the ceiling joists, around a beam, and out through a rim joist or a foundation wall. Every foot of duct and every elbow adds resistance. Manufacturers publish a maximum vent length for each model, which gets shorter with each bend, and older installations sometimes exceed it without anyone realizing.
Things to look at:
- •Flexible foil or vinyl hose behind the dryer. Thin foil crushes easily when the dryer is pushed back. Vinyl hose isn't meant for dryer exhaust at all. Semi-rigid or rigid metal duct keeps its shape and collects less lint.
- •Long horizontal runs. Lint settles in the low spots, especially where a run sags between hangers.
- •Joints held with screws. Screws that poke into the duct catch lint and build a plug around themselves. Foil tape is the better fastener.
- •The outside hood. Go outside while the dryer runs. You should feel a strong, warm flow and see the flap open wide. A weak puff or no movement means a restriction somewhere.
Winter makes vents worse
Warm, wet air cools as it moves through a duct in an unheated basement or crawl space. Some of the moisture condenses on the inside of the duct, and lint sticks to the damp spots. Over a winter, a run that was fine in September can narrow noticeably.
The hood itself can also give trouble in cold weather. Condensation can freeze the flap shut, and snow drifts or plowed snow can bury a low hood on the side of the house. If drying slowed down after a snowfall or a hard freeze, check the hood before anything else. Later in the year, birds and wasps like dryer hoods, so a nest is worth ruling out too.
Lint screen and lint chute
Clean the lint screen before every load, and every so often scrub it under the tap with dish soap and an old toothbrush. Dryer sheets leave a waxy film that you can't see but that water will bead on. Below the screen is a chute that also collects lint. A long, flexible lint brush or a vacuum crevice tool will reach most of it.
A simple airflow test
Disconnect the duct from the back of an electric dryer, put the lint screen in, and run it on a timed dry setting for a few minutes with a damp towel. If it now dries noticeably faster, the restriction is in the vent, not the machine. Reconnect everything afterward. Don't do this with a gas dryer, for the carbon monoxide reason above.
When the dryer produces no heat at all
If the vent is clear and the drum turns but never warms, a part has probably failed. Which parts depends on the fuel.
Electric dryers
- •Tripped breaker, half on. An electric dryer's breaker is a double breaker. If one half trips, the motor can still run on the other while the heating element gets nothing. Switch the breaker fully off, then on.
- •Thermal fuse. A one-time safety fuse on the blower housing or exhaust duct. When it blows, the dryer may not heat, or on some models won't run at all. A blown thermal fuse almost always means the dryer overheated, often because of the vent. Replacing the fuse without fixing the airflow sets it up to blow again.
- •Heating element. A coil of resistance wire that can break. Sometimes you can see the break through the element housing.
- •High-limit or cycling thermostat. These switches control and protect the element and can fail open.
Gas dryers
- •Closed gas valve. After a move, a remodel or a water heater service, the shutoff valve behind the dryer is sometimes left closed.
- •Igniter doesn't glow. Watch through the small viewing hole near the burner (many models have one on the front or lower panel). If the igniter never glows, suspect the igniter itself, the flame sensor, or the thermal fuse.
- •Igniter glows, then goes dark with no flame. This is the classic sign of weak gas valve coils. The igniter heats up, but the valve never opens to let gas through.
- •Flame lights, then goes out quickly and the cycle repeats. This can be a cycling thermostat doing its job on a restricted vent, or a component beginning to fail.
A multimeter will confirm most of these parts, but testing inside a gas dryer means working near the burner assembly. If you aren't comfortable with that, it's a good place to stop.
Signs that shouldn't wait
Shut the dryer off and don't use it until it's been checked if you notice:
- •A burning or scorched smell
- •The outside of the cabinet too hot to keep your hand on
- •Scorch marks on clothes
- •Lint visible around the burner or element
- •A thermal fuse that keeps blowing
These usually trace back to trapped heat, and lint is flammable.
Getting it fixed
A technician will look at the vent run as part of the diagnosis, test the heating circuit or gas train, and explain which part failed and why. You'll get a price for the repair before any work begins. If the vent is the real problem and a new part would only fail again, we'll tell you that first. Vent cleaning and rerouting a long run may be a separate job from the dryer repair itself.
You can call or book dryer repair online.