The most common cause is restricted airflow, a lint filter coated with softener film or a vent that is clogged with lint. Both are worth checking first, and a clogged vent is also a fire risk. If the airflow is fine, look at the load size, the washer's spin, and the moisture sensor before suspecting a heating part. Working through the causes below in order will point you toward the real issue fastest.
When a dryer needs two cycles to dry one load, it is easy to assume the heating has failed. In practice, the cause is often something simple, a filter that looks clean but is not or a vent that has slowly filled with lint, sitting alongside a few causes that genuinely do need a licensed technician.
Below are the eight causes we see most often, ordered from most to least common, along with the signs that separate one from another and an honest answer on whether it is safe to check yourself.
Jump to a cause
Clogged lint filter
The lint filter does more than catch lint. Fabric softener and dryer sheets leave a thin, nearly invisible film on the mesh that blocks air even when the filter looks clean, so moist air cannot leave the drum.
- Clothes come out hot but still damp
- The filter has never been washed, only wiped
- Water poured on the dry mesh sits on top instead of draining through
- Dryer sheets or liquid softener are used with most loads
Blocked or crushed exhaust vent duct
The duct carries hot, moist air from the dryer to the outside. Lint builds up inside it over time, and a duct that is crushed, kinked behind the dryer, or very long can restrict the airflow badly.
- Drying times have grown longer gradually over months
- The back of the dryer and the surrounding wall feel unusually hot
- The duct looks flattened or sharply bent behind the dryer
- The vent has not been cleaned in over a year
Stuck or blocked outside vent hood
At the end of the duct, a flap or hood lets the air escape. If the flap is stuck closed, clogged with lint, or blocked by a nest or debris, the dryer cannot push its air outside.
- Little or no air comes out of the outside hood while the dryer runs
- The flap does not open or stays partly closed
- Lint is visible around the hood or on the wall outside
- The hood is covered by a screen clogged with lint
Overloaded drum or the wrong cycle
Clothes need room to tumble so air can flow through them. An overstuffed drum, a few heavy items such as towels or jeans, or a cycle set to low heat or to a short sensor cycle can leave a load damp.
- Large loads or bulky items such as comforters come out damp
- Towels and jeans are damp while lighter items are dry
- The cycle is set to low heat, delicates, or a short timer
- Splitting the load into two smaller ones dries it properly
Clothes arriving too wet from the washer
A dryer can only remove so much water. If the washer does not spin clothes out well, because of an overloaded drum, a slow drain, or a spin problem, the dryer starts with soaking wet laundry and takes far longer.
- Clothes come out of the washer dripping or very heavy
- The washer leaves water in the tub at the end of the cycle
- Drying times jumped after a change on the washer side
- The dryer works normally with hand-wrung clothes
Dirty or failing moisture sensor
Many dryers use sensor bars inside the drum to decide when clothes are dry. A coating of softener residue can make them misread the load, so the cycle ends too early or runs far longer than needed.
- The cycle ends while clothes are still damp
- The auto-dry cycle runs much longer than a timed one
- Two thin metal bars inside the drum look coated or dull
- A timed cycle dries clothes better than an automatic one
Weak heat from the heating element, igniter, or thermostat
If the heating parts are failing, the dryer still tumbles and makes warm air, but not enough to dry a load in the normal time. If there is no heat at all, see our guide to a dryer that runs but won't heat.
- Clothes come out only warm, never really hot
- The drum feels lukewarm after a full cycle
- The problem remains after the filter and vent are clean
- Drying gets slower and slower rather than failing suddenly
Worn blower wheel or drive parts
The blower wheel pulls air through the drum and out of the vent. If it is clogged, cracked, or loose on its shaft, or the motor driving it is worn, the airflow drops even when the vent is clear.
- The vent is clear, but very little air reaches the outside hood
- A rattling, squealing, or thumping noise comes from the dryer
- The motor sounds strained, or the drum turns slowly
- The dryer is several years old and has had heavy use
Not sure which one matches? Start here
Clothes come out hot but still damp
- Most likely: vent duct or lint filter
- Also check: outside vent hood
The drum feels only warm, and drying keeps getting slower
- Most likely: weak heating parts
- Also check: the load and cycle and blower wheel
Not sure which one it is?
Skip the guesswork. Tell us what you're seeing and a technician will help pin down the cause.
What to check yourself first
These items are safe to check with a soft brush, soap and water, and a flashlight. Give the dryer a test load after each step to see whether the drying time improves.
Unplug the dryer before cleaning inside it or behind it. On a gas dryer, do not strain or disconnect the gas line when moving it, and call a technician right away if you smell gas. Lint packed in a vent is a fire hazard, so do not ignore a clogged vent.
Clean the lint filter. Wash it with warm soapy water and let it dry to remove the invisible film.
Check the load. Dry smaller loads and separate heavy items from light ones.
Look at the duct behind the dryer. Check for crushing, sharp bends, or heavy lint.
Check the outside vent hood while the dryer runs. The flap should open and air should flow out.
Wipe the moisture sensor bars inside the drum with a cloth dampened with rubbing alcohol.
When to call a professional
Some signs point straight to a licensed technician rather than a DIY fix. Call for service if you notice any of the following:
- A burning smell, or an outer cabinet that feels very hot
- The filter and vent are clean, but drying still takes two cycles
- Lint or damp air coming out around the dryer instead of the outside vent
- A rattling or squealing noise, or a dryer that shuts off mid-cycle
- The dryer is still under manufacturer warranty, since a DIY repair can void it
Revive Appliance Repair handles dryers that take too long to dry for homes and businesses throughout Walnut Creek and the surrounding service area. Our dryer repair service covers diagnosis through completed repair, backed by a 90-day labor warranty.
You may also find these guides useful: troubleshooting a dryer that runs but won't heat and a washer shaking during the spin cycle.