Why your dryer takes two cycles to dry

If a load of towels needs two full runs to come out dry, the dryer is telling you something. Most of the time the cause is airflow. Warm, wet air has to leave the drum and get outside, and when it can't, the clothes just sit in it.

You can check most of this yourself in under an hour. Here's the order we'd go in, starting with the quick stuff.

A quick safety note first. Unplug the dryer before you pull it away from the wall or touch anything behind it. If it's a gas dryer, move it slowly so you don't strain or kink the gas line. If you ever smell gas, leave the house and call your gas company from outside.

1. Clean the lint screen properly

You probably already empty it. Whirlpool says to do it before every load, and the U.S. Fire Administration says before and after each cycle.

Dryer sheets and fabric softener can also leave a film on the mesh that you can't really see. Whirlpool recommends washing the screen with warm water and a soft brush, then letting it dry completely before you put it back. Never run the dryer without the screen in place.

2. Look at the size of the load

Clothes need room to tumble. Whirlpool suggests filling the drum about half to three quarters full. A packed drum dries slowly because air can't get between the layers.

Very small loads cause a different problem. Sensor dryers read moisture through metal bars inside the drum, and a couple of shirts may never touch them. Samsung puts the minimum at about four regular bath towels' worth of laundry.

3. Check the cycle settings

Air only and low heat settings are slow by design. Some Samsung models also have an Eco Dry option that cuts heat to save energy, and it can switch on with Normal or Time Dry cycles. If you're using a sensor cycle and the clothes come out damp, try a higher dry level before you assume something is broken.

4. Wipe the moisture sensor bars

On sensor models there are two curved metal strips inside the front of the drum. Residue from dryer sheets coats them, and the dryer can think the load is dry before it is. Samsung recommends cleaning them with a soft cloth and a drop of dish soap.

5. Check the vent, which is the usual cause

Whirlpool puts it plainly: if the dryer heats but still takes a long time, the most likely cause is a restricted vent. Here's how to check yours.

1. Pull the dryer out a little and look at the duct behind it. Dryers get pushed back against the wall and the duct gets crushed. Both Whirlpool and the U.S. Fire Administration call this out.
2. Look at what the duct is made of. Whirlpool recommends 4 inch rigid or flexible metal duct and says foil and plastic aren't recommended because they collapse easily.
3. Think about the length of the run. Every 90 degree turn shortens the allowed length by about six feet, according to Samsung. Whirlpool says many dryers work well when the total equivalent length stays under 35 feet. Your manual lists the limit for your model.
4. Go outside while the dryer runs on a heat setting. The flap on the outside vent hood should push open. If it barely moves, air isn't getting through. Clear out any lint, leaves or nests you find there.
5. Check the hood's position. Whirlpool says it should sit at least 12 inches above the ground or anything that could block it.

Some newer dryers have a vent test built in, and Samsung documents one for many of its models. Look in your manual for it. It takes a few minutes and tells you whether the dryer sees a blockage.

How often should the vent be cleaned? Whirlpool says every one to two years. Samsung says once or twice a year. Either way, do it sooner if drying times start creeping up.

Why a slow dryer is a fire safety issue

This part matters more than the electric bill. The U.S. Fire Administration says your risk of a dryer fire goes up when you don't clean the lint filter and the vents. Older Consumer Product Safety Commission research found that lint fires often start in the lint trap, and that slow drying is often the only warning a dryer gives when its airflow is restricted.

So if your clothes are taking twice as long, treat it as a signal. Clean the lint screen, check the duct, and clean the area behind the dryer where lint collects. If you smell something burning, stop using the dryer until it's been looked at.

If the dryer runs but barely heats

Whirlpool has a simple test. Run the empty dryer on a heated setting for five minutes, then open the door and feel inside. If it isn't warm, the problem is heat, not airflow.

• On a gas dryer, make sure the gas supply valve is open.
• On an electric dryer, check the breaker. Samsung notes that electric dryers need a 240 volt outlet, and suggests switching the breaker off for 30 seconds and back on.

If that doesn't bring the heat back, the cause is usually a part. On electric models it could be the heating element. Many dryers also have a thermal fuse, a safety part that cuts power when the dryer overheats. Once it trips it can't be reset, and on many models the dryer won't start at all.

Here's the catch. Parts supplier PartSelect lists a restricted exhaust vent as a common reason thermal fuses blow. Put in a new fuse without fixing the vent and it can fail again. That's why we check airflow on every dryer call, even when the visible problem is a dead part.

When to call us

• The vent is clean, the outside flap opens, and loads still take two cycles.
• The dryer has no heat, or it won't start.
• You smell burning, or the dryer cabinet feels much hotter than usual.
• You'd rather not take panels off or test parts with a multimeter.

If your duct runs a long way through walls or up to the roof, a dryer vent cleaning service has the equipment for that run. We can tell you whether the dryer itself is healthy.

Repair or replace?

Most slow drying problems come down to airflow or a single failed part, and those are usually worth fixing. If your dryer needs a major part and it's getting older, we'll show you the numbers and tell you honestly whether replacing it makes more sense. You decide after the $129 diagnostic, and that fee is credited to the repair if you go ahead.