When a dryer starts needing two or three cycles to finish a load, most people assume the heating element is going. Sometimes it is. But very often the dryer is heating just fine and the hot, wet air has nowhere to go. The problem is in the vent.
That matters for more than your electric or gas bill. A restricted vent makes the dryer run hotter and longer, and lint is highly flammable. This guide explains how dryer vents are typically routed in San Antonio homes, what you can check, and when to stop using the dryer until it's inspected.
How a dryer actually dries
A dryer heats air, pushes it through the tumbling clothes, and exhausts it outside, carrying the moisture with it. The exhaust side is as important as the heat. If the air can't leave quickly, it stays humid, the clothes stay damp, and the dryer's thermostats cycle the heat off to protect the machine. You end up with a dryer that runs for a long time without drying much.
Why vent runs are long in many San Antonio homes
Most homes here are built on slab foundations, with no basement or crawlspace under the laundry area. In homes where the laundry is on an interior wall, the vent often has to go up through the attic and out through the roof, or run a long way to reach an outside wall. That's normal construction, but it has consequences:
- •Longer runs collect more lint and need cleaning more often.
- •Roof terminations can be blocked by lint caught in the cap, bird nests, or a damper stuck shut.
- •Vertical runs mean lint and condensation can settle back down toward the dryer.
- •Joints in the attic can separate over time, dumping hot, moist air and lint into the attic instead of outside.
Laundry in the garage usually has a shorter path to an outside wall, which is easier on the dryer. The dryer manual lists the maximum vent length for that model, reduced for each elbow. If a vent run exceeds it, the dryer will struggle no matter how clean it is. Older homes where the laundry was moved into an addition or a converted porch can have similarly long routes, which our guide to modern appliances in historic homes touches on.
What you can check yourself
Unplug an electric dryer before moving it. For a gas dryer, turn the gas supply valve off before pulling it out, and move it carefully so you don't strain the gas connector.
1. The lint screen
Clean it before every load. Once a month, wash it with warm water and dish soap and a soft brush. Dryer sheets can leave a waxy film on the mesh that blocks airflow even when it looks clean. Hold it under a running tap. If water pools on the screen instead of passing through, it needs scrubbing.
2. The lint screen housing
With the screen out, look down into the slot. Lint builds up below the screen. A narrow vacuum attachment or a flexible dryer lint brush removes most of it.
3. The transition duct behind the dryer
This is the short connection between the dryer and the wall. It should be rigid or semi-rigid metal duct. White vinyl or thin foil accordion duct shouldn't be used. Both crush easily, trap lint, and many dryer manufacturers don't allow them. Make sure the duct isn't crushed behind the dryer when it's pushed back.
4. The outside termination
Run the dryer on a heat setting and go outside to the vent cap, whether on a wall or on the roof. If it's on the roof, look from the ground and don't climb up unless you're comfortable and safe doing so. You should see or feel a strong flow of warm air. A flap that barely moves, or no visible exhaust, means the vent is restricted. Check the cap for lint buildup, a stuck damper, or a screen. Screens on dryer vent caps trap lint and shouldn't be used.
5. Compare airflow at both ends
Pull the transition duct off the wall connection. With the dryer on the air-only (no heat) setting, feel the airflow from the end of the duct for a few seconds, then compare it with what you felt at the outside cap. Strong at the dryer but weak outside means the restriction is in the vent run. Weak at the dryer itself points to lint inside the dryer or a blower problem. Keep this test short, use only the no-heat setting, and reconnect the duct firmly before running a heated cycle. Never run a gas dryer on heat with the duct disconnected.
Cleaning the vent
A dryer vent cleaning kit with a rotating brush on flexible rods can clear a short, straight run from the wall end. Long attic runs and roof terminations are harder. Pushing lint toward a roof cap can pack it tighter, and a rod can separate a joint you can't see. For those, a professional vent cleaning service is the sensible choice. How often depends on the run and how much laundry you do. Once a year is a common baseline, sooner if drying times start creeping up.
Signs of a fire risk
Stop using the dryer and have the vent and the dryer checked if you notice:
- •The top or sides of the dryer are hot to the touch, hotter than usual.
- •A burning or scorched smell during a cycle.
- •The laundry room gets hot and humid while the dryer runs.
- •Clothes are very hot but still damp at the end of the cycle.
- •Lint around the door opening or behind the dryer that keeps coming back.
Some dryers have a thermal fuse that blows when the machine overheats, and the dryer stops heating or won't start. Replacing the fuse without fixing the vent problem that caused it just sets up the next failure.
When the dryer itself is at fault
If the vent is clean and the airflow outside is strong, but the dryer still doesn't dry well, the fault is inside the machine. Common causes include:
- •Electric dryers: a failed heating element, a blown thermal fuse, a cycling or high-limit thermostat, or one leg of the 240-volt supply being out. A tripped breaker on one side can let the drum turn with no heat.
- •Gas dryers: a weak igniter, failed gas valve coils or a flame sensor problem. If you smell gas, don't operate the dryer or any switches. Leave the house and call CPS Energy's gas emergency line or 911 from outside.
- •Both types: a moisture sensor coated with fabric softener residue can end auto-dry cycles too early. Wipe the metal sensor bars inside the drum with a little rubbing alcohol.
These are repairs for a technician. See our dryer repair page for what's involved, and the matching washer repair page if the washer isn't spinning water out well, because a load that leaves the washer soaking wet takes much longer to dry.
Frequently asked questions
How long should a normal load take to dry?
It depends on the load and the machine, but a typical mixed load usually finishes within one normal timed cycle. If it now takes noticeably longer than it used to, something has changed.
Is a roof vent worse than a wall vent?
Not inherently, but roof vents tend to be longer, harder to inspect and harder to clean. They need regular attention.
My dryer is new and still takes two cycles. Why?
That usually points to the vent or the installation: a crushed transition duct, a vent run longer than the manual allows, or an old vent that was never cleaned when the new dryer went in.