A dryer that tumbles happily for an hour and hands back a load of damp towels is the single most common fault we are called out to. It is also the one where the appliance is most often innocent.
Heat is only half of drying. The other half is getting moist air out of the drum and outside the house. When that path is restricted, the machine keeps heating, the air keeps saturating, and nothing dries. The dryer is working exactly as designed and failing anyway.
Here is how to narrow it down before you pay anyone to look at it.
Start with the cycle time, not the clothes
Think back six months. A load that used to finish in 45 minutes and now takes 90 is the clearest signal there is, and it points at the vent almost every time. Restriction builds gradually as lint packs into the duct, so the slide from 45 minutes to 60 to 90 happens slowly enough that most households never notice it.
If the change was sudden, from working to not working inside a single week, the vent is less likely and a component has probably failed.
Six causes, in the order we check them
1. A blocked or crushed vent duct
Go outside and find the vent flap while a load is running. You should feel a strong push of warm, damp air. If it is a weak trickle, or the flap is barely lifting, that is your fault.
Flexible foil ducting behind the machine is a common culprit. It crushes when the dryer is pushed back against the wall, and every crush point catches lint. Rigid metal duct with as few elbows as possible is what you want.
This is also a fire risk rather than just an inconvenience. Lint packed against a heat source is exactly the condition that causes dryer fires, so it is worth dealing with regardless of the drying time.
2. A clogged lint filter, including the housing below it
Everyone cleans the lint screen. Far fewer people look down into the slot the screen sits in. Lint accumulates in that cavity and in the blower housing beneath it, and neither is visible from the top.
If your screen looks clean but water beads on it when you run it under a tap, that is fabric softener residue sealing the mesh. Scrub it with a soft brush and warm soapy water.
3. A failed heating element or gas valve coil
If the vent is clear and the cycle time did not creep up gradually, the heat source is the next suspect. On an electric dryer, that is the heating element. On a gas dryer, it is the igniter or the valve coils.
A quick test with no tools: run a cycle for ten minutes, then open the door and put a hand near the drum wall. It should be genuinely hot, not warm. Warm means the element is not firing.
4. A tripped thermal fuse
This one is a consequence rather than a cause. Thermal fuses are one-shot safety devices that blow when the cabinet overheats, and cabinets overheat when the vent is blocked. On many models the drum still turns after the fuse blows, which is why the machine appears to work while producing no heat at all.
Replacing the fuse without clearing the vent guarantees you will be replacing it again.
5. A cycling or high-limit thermostat
These regulate the temperature the element runs at. When one fails open, you get no heat. When one fails closed, you get too much heat and then a blown thermal fuse. Both are inexpensive parts.
6. Overloading
Worth ruling out, because it costs nothing. A drum packed past about three quarters full cannot tumble properly, and clothes that do not tumble do not dry. If a half load dries fine and a full load does not, nothing is broken.
What you can safely do yourself
Pull the machine out and disconnect the duct from the back. Vacuum both the duct and the port on the dryer. Go outside and check the flap moves freely and is not blocked by a bird's nest, which is more common than it sounds.
Clean the lint screen properly, and vacuum out the slot it sits in with a narrow crevice tool.
Run a load and time it. If it is back to normal, you have solved it for the price of an afternoon.
Where to stop
Do not open the cabinet. On an electric dryer that means working around a 240-volt circuit. On a gas dryer it means working around a gas connection. Neither is a good place to learn.
If the vent is clear and the drum is not getting hot, the fault is inside the machine and it needs someone with a multimeter and the model's wiring diagram.
What a repair usually involves
We check the vent first, on every no-heat call, whatever the customer thinks the problem is. Then we test the element or valve coils, the thermal fuse and the thermostats in that order, because that is the order they fail in.
All four are stocked parts on our vans, so most no-heat dryer calls finish in a single visit of under 90 minutes. See what we carry and what a dryer visit involves.
FAQ
How often should a dryer vent be cleaned?
Once a year for an average household. More often if the duct run is long, has several bends, or you dry heavy items like towels and bedding regularly.
Is a blocked vent really a fire risk?
Yes. Lint is highly combustible and a restricted duct traps it against a heat source. Clothes dryers are a recognised cause of house fires in the United States, and blocked venting is the leading contributing factor.
My dryer heats but the clothes are damp on one side only.
That is tumbling, not heat. Check the drum baffles are intact and that you are not overloading. A worn drum roller can also let the drum sit off-centre.
Can I use a heat pump dryer with no external vent?
Yes, and they are excellent in apartments. They have their own maintenance need though: a condenser unit and a second lint filter, both of which need cleaning far more often than people expect.
Is a dryer worth repairing?
Almost always. The common failures are inexpensive parts and the cabinet, drum and motor generally outlast them by years.
If your dryer is still not drying after you have cleared the vent, we cover 155 towns across Greater Boston and Southern New Hampshire with same-day slots.
