Why your clothes dryer is taking two cycles to finish the job

A dryer that needs two cycles has a restricted airflow. That is the answer in nine cases out of ten, and it is a safety problem as much as an inconvenience.

A dryer does not dry clothes with heat alone. It heats air, moves it through the drum, and carries the moisture out through the vent. Stop the air moving and the heat has nowhere to take the water.

Start at the lint filter

Clean it every load, which most people do.

Then do the water test, which almost nobody does. Take the filter out and run water onto it. If the water pools and sits rather than running straight through, the mesh is blocked by a film.

That film builds up from dryer sheets and fabric softener over months. It is invisible. It restricts airflow badly.

Scrub it with warm soapy water and a soft brush, rinse, dry completely, put it back. Do this every few months.

Then the vent

This is the big one and it is where the fire risk lives.

Disconnect the duct at the back of the dryer and look inside both the machine outlet and the duct. Lint accumulates in the duct, and the further along it accumulates, the worse it gets.

Go outside and find the vent hood while the dryer is running. You should feel strong air. If you feel a weak breeze, the run is blocked somewhere.

Check the flap on the hood. They get stuck with lint, and birds nest behind them. I have pulled entire nests out of vent hoods in the spring.

Look at the duct material. Flexible plastic or foil duct is the worst thing you can have. It sags, it traps lint in every ridge, and in some places it is not permitted. Rigid metal duct is what you want, with the shortest run and fewest bends you can manage.

Every elbow costs you airflow. A long run with four bends will never dry well no matter what else you fix.

Other causes

An overloaded drum. Clothes need room to tumble and air needs room to circulate. Half to two thirds full is right.

A washer that is not spinning properly. If clothes come out of the washer wetter than they used to, the dryer is being asked to remove far more water. Test by weighing a load, or just by feel. This gets misdiagnosed as a dryer problem constantly.

A failing heating element or a bad thermostat on an electric dryer. The symptom here is different: the drum turns, the cycle runs, and the air is barely warm.

On a gas dryer, an igniter or flame sensor problem produces the same cold result.

A dead moisture sensor, which makes automatic cycles stop early. Use a timed cycle for a load and see whether it dries properly. If timed works and automatic does not, that is your answer, and the sensor bars inside the drum may just need wiping with rubbing alcohol.

Why I keep pushing on this

Restricted dryer venting is a genuine cause of house fires. It is one of the few appliance faults where the failure mode is not just an expensive repair.

A dryer that is running hot because it cannot expel air is a dryer sitting near a duct packed with lint.

If your machine needs two cycles, it has been telling you this for a while.

What to do this weekend

Pull the machine out. Disconnect the duct, clean it properly with a brush, replace it with rigid metal if it is not already. Clean the hood outside and check the flap moves.

Wash the lint filter. Wipe the moisture sensor.

Then run a normal load and see. Most people who do this find the load dries in one cycle for the first time in two years, and the machine they were about to replace is fine.