If you fix nothing else on a dryer, clean the vent. Restricted airflow is behind more dryer complaints — long dry times, no heat, overheating, a blown thermal fuse, even some noises — than every other cause put together. It is also the one maintenance job most people never do, because unlike a washing machine filter, a dryer vent is mostly out of sight.
How a dryer actually works
A dryer does two things at once: it tumbles the drum to expose wet clothes to airflow, and it moves a steady volume of heated air through that drum and out through a vent to the outside. Both have to work together — tumbling without heat just spins damp clothes, and heat without airflow has nowhere to carry the moisture.
That second half — moving air out of the house — is where nearly everything goes wrong, because the vent run is the one part of the system that clogs gradually and invisibly over months of use.
Find your fault by symptom
| Symptom | Most likely cause | Full guide |
|---|---|---|
| Runs but blows cold air | Blocked vent, blown thermal fuse, or failed heating element | Dryer not heating |
| Takes much longer than it used to | Restricted vent — the classic early warning sign | See the vent section below |
| Will not start at all | Power, door switch, or a tripped thermal overload | Dryer will not start |
| Drum does not turn, motor hums | Broken drive belt or a seized idler pulley | Dryer drum not turning |
| Smells like burning | Lint accumulation or an electrical fault — stop and investigate immediately | Dryer smells like burning |
| Squealing or screeching | Worn drum support rollers or a glazed belt | Related problems below |
| Gets far too hot to touch | Restricted vent forcing heat to build up in the cabinet | See the vent section below |
| Damp patch on one side of the load | Uneven tumbling, often a worn drum roller or belt | Related problems below |
Why the vent matters more than any part
Lint does not stop at the trap. A fine layer passes through every load and settles inside the duct, and over months that layer narrows the passage until the dryer is pushing hot, moist air through what amounts to a drinking straw. The consequences build in a predictable order:
- Dry times creep up
This is the first and most reliable warning sign, and the one almost everyone ignores. A load that used to take 45 minutes now takes 70, then 90.
- The cabinet runs hot
With nowhere for the heat to escape, it builds up inside the machine. You will notice the top and front panel getting noticeably warmer than before.
- The thermal fuse blows
This is a one-time safety fuse designed to cut power if the machine overheats. Once it has blown, the dryer runs with no heat at all — and fitting a new fuse without clearing the vent means the new one blows too.
- In the worst case, lint ignites
Restricted dryer venting is a well-documented residential fire risk. This is not a hypothetical — it is the entire reason vent cleaning is worth taking seriously rather than treating as optional housekeeping.
Disconnect the vent duct from the back of the machine and clear it end to end with a vent brush, working from both ends if you can. Check the exterior wall flap opens freely and is not blocked by lint, a bird’s nest or debris. Do this at least once a year, more often if dry times have been creeping up.
Gas dryers are different
Everything above about airflow applies equally to gas dryers, but the heat source itself introduces faults electric dryers do not have: an igniter that fails to glow, gas valve coils that do not open, or a flame sensor that shuts the burner off prematurely. Diagnosing beyond checking the vent and observing the ignition sequence — watching whether the igniter glows, then the valve opens, then the flame lights — should be left to a qualified gas engineer. Gas work sits outside safe DIY territory in a way electrical dryer faults generally do not.
Repair or replace?
Cheap and worth doing at almost any age: thermal fuses, drive belts, idler pulleys, drum support rollers, door switches, and vent cleaning. Expensive and worth thinking hard about: the motor, the control board, and the drum itself if it has been damaged by a seized bearing. On a dryer past roughly ten to twelve years, a major component failure is usually the point where a new machine makes more sense — dryers are mechanically simple enough that most of their lifespan is determined by how well the vent was maintained, not by the machine’s inherent quality.
When to call a professional
Call an electrician if the dryer trips the breaker repeatedly — our circuit breaker guide covers diagnosing that from the electrical side. Call a gas engineer for any fault beyond the vent and basic ignition observation on a gas machine. Call an appliance engineer for belt, motor, drum roller or control board work, all of which mean opening the cabinet around a mains supply that draws heavily.
Stop and call a qualified appliance technician or electrician if you find scorched or melted wiring, smell burning, see water that has reached electrical components, or if the fault returns immediately after a repair. Never bypass a safety device — thermal fuses, door interlocks and flood switches fail for a reason, and defeating one converts a broken appliance into a fire or flood risk.
