Dryer Not Heating: Causes for Electric and Gas Models

A dryer not heating at all is a different fault from a dryer that heats fine and still needs three cycles to dry a load of towels. The first means the heat source is switched off, and the fix is rarely a part inside the cabinet: it is the electrical supply on an electric machine or the gas shutoff valve on a gas one. The second means air is not moving, and that is almost always the vent. Sort your symptom into the right group before you order anything.

This post splits the no heat causes by fuel type, lists the slow drying causes in the order worth checking, sets out the duct rules the code and the manuals impose, and covers the fire and carbon monoxide risks a restricted vent creates. Every number comes from a named primary source: the US Fire Administration, CPSC, the Department of Energy, HUD, the residential mechanical code as published by an adopting US city, and manufacturer documents from Whirlpool, GE Appliances, LG, Samsung and Frigidaire.

Key takeaways

Whirlpool states that an electric dryer sits on a 30 amp circuit fused on both sides, one breaker for the motor and one for the element, so half a tripped breaker gives tumble without heat.
GE Appliances states that an electric dryer may run on a partial 120 volt supply but will not heat unless it has 208 or 240 volts.
Whirlpool states that a gas dryer’s drum turns but will not heat if the gas shutoff valve is closed, and the valve is open when the handle is parallel to the pipe.
The US Fire Administration counted an estimated 2,900 clothes dryer fires a year in residential buildings from 2008 to 2010, with 5 deaths, 100 injuries and $35 million in loss.
The residential code caps a dryer exhaust duct at 35 feet, minus 5 feet per 90 degree elbow and 2 feet 6 inches per 45 degree elbow.

No heat and slow drying are two separate faults

Separate the symptoms before touching anything. A dryer with no heat leaves the load cold and the drum at room temperature after a full heated cycle. A dryer with restricted airflow gets hot, sometimes hotter than it should, and still returns damp clothes.

Whirlpool publishes a test that settles it: run a heated timed cycle empty for five minutes, then feel inside the drum. Warm means airflow. Room temperature means the heat source is off.

Check the cycle setting first. Whirlpool notes that the Air Only or Air Fluff Only cycle never adds heat, and Frigidaire lists it as a cause of a cold load.

What you see	Most likely cause	First thing to check
Drum turns, load cold, electric dryer	One half of the 240 volt circuit is open	Both breakers or both fuses, fully cycled off and on
Drum turns, load cold, gas dryer	Gas shutoff valve closed or supply interrupted	Valve handle parallel to the pipe, other gas appliances
Drum turns, load cold, either type	An unheated cycle is selected	Air Only, Air Fluff or a no heat setting on the dial
Drum hot, clothes damp, long cycles	Restricted airflow through the vent	Lint screen, transition duct, outside hood flap
Weak heat and rising cycle times	Controls cutting heat because exhaust is blocked	The machine’s vent blockage test or error code

Electric dryers: two breakers and a 240 volt supply

An electric dryer uses 240 volts to make heat and 120 volts to turn the drum and run the controls. That split produces a machine that tumbles on time, beeps, and dries nothing.

Whirlpool states that electric dryers require a separate 30 amp circuit fused on both sides of the line, so two breakers or two fuses operate the dryer. One operates the motor and the other operates the heating element, and if one is tripped the dryer may not heat. Frigidaire puts it plainly: if one of the two house circuits or fuses is tripped or blown, the drum may turn but the heater will not operate.

A double pole breaker can lose one pole without the handle moving far enough to look tripped, so a visual check is not enough. GE Appliances tells you to turn the breaker off and back on, and states that an electric dryer may run with a partial voltage of 120 volts but will not heat unless it has a 208 volt or 240 volt power supply. In an older panel, Whirlpool tells you to confirm both cartridge fuses are intact and tight.

If the breaker holds and there is still no heat, the candidates move inside the cabinet. Whirlpool names a faulty heating element or a blown thermal fuse, and Samsung says a blown thermal fuse needs professional repair. Before calling, inspect the cord and terminal block for the burnt or loose connections GE describes.

Gas dryers: the shutoff valve and the glow bar igniter

A gas dryer still plugs into an ordinary 120 volt outlet for the motor and controls. Its heat comes from a burner, so a gas dryer with no gas behaves exactly like an electric dryer with one tripped breaker.

Whirlpool states that the drum of a gas dryer will turn but the dryer will not heat if the gas shutoff valve is closed, and that the valve is open when the handle is parallel to the pipe. Frigidaire adds the supply side cases: an empty LP tank, or an interrupted natural gas service. If other gas appliances are dead too, the fault is the supply, and the same reasoning covers a furnace that will not turn on.

Where gas is present, ignition runs as a sequence. GE Appliances describes a glow bar igniter with no moving parts that removes the need for a standing pilot. The glow bar comes on roughly 15 seconds after the dryer starts, and once it is hot enough a sensor tells the gas valve to open. The gas lights, the flame heats the bar, and the bar cycles off. GE is explicit that the gas will not be dispersed unless the glow bar is working properly. The burner housing sits behind a panel with a live gas line, which is where an owner check ends.

A check order for a dryer that tumbles without heat

Work through these in order. Each step either finds the fault or clears a group of causes.

Confirm the selected cycle adds heat. Air Only and Air Fluff tumble a cold load all afternoon.
Run an empty heated timed cycle for five minutes and feel inside the drum. Warm means heat works.
On an electric dryer, switch the breaker fully off and back on, and check both cartridge fuses rather than the one that looks blown.
On a gas dryer, look at the shutoff valve handle behind the machine. Parallel to the pipe means open. Then check other gas appliances.
Clean the lint screen, pull the dryer forward and check that the transition duct is connected, uncrushed and unkinked.
Go outside with the dryer running and hold a hand at the vent hood. GE states that the outside cap must open and close as air passes through.
If heat is still absent and the supply is good, stop. What remains is the element, thermal fuse, thermostats, igniter or gas valve, which Whirlpool and Samsung refer to a technician.

Why a dryer that heats still takes three cycles

A dryer that clearly heats and still needs two or three cycles is short of air. The machine heats air, the air picks up moisture, and the vent carries it outside. Restrict the vent and the same humid air circulates instead of leaving, so the load stays damp and the cycle time climbs.

Manufacturers measure this now. LG’s d90 code means the ductwork is about 90 percent blocked and d95 means about 95 percent, and LG warns that using a dryer with a severely restricted exhaust may create an unsafe environment. Samsung’s vent blockage test runs on an empty drum and returns 0 or End for a clear system, C8 or C80 for about 80 percent clogged, and C9 or C90 for about 90 percent.

Samsung is direct about the mechanism: a vent that is not clean causes blockages which prevent heat and moisture from escaping and cause the dryer to reduce its heat. So a blocked vent can present as weak heat rather than long cycles.

Work the restrictions from cheapest to hardest. Whirlpool notes that a blocked lint screen increases drying time, and recommends a deep clean with soap, water and a nylon brush every six months because fabric softener leaves a film. Energy Star says the same of dryer sheet residue. Next comes the transition duct, then the duct in the wall, then the hood outside. Whirlpool says the venting should be cleaned every one to two years. The logic behind how often to change a furnace filter applies here: a restriction you cannot see still costs you airflow.

What the code and the manuals require of your duct

Duct length and material are not preferences. The International Residential Code sets them, and adopting jurisdictions publish the text. Seattle’s residential code carries the 2021 version.

Section M1502 requires an exhaust duct with a smooth interior finish, made of metal not less than 0.0157 inch thick, 4 inches nominal in diameter. Joints must not use fasteners that protrude more than one eighth of an inch into the duct, because anything projecting inward collects lint. The maximum length is 35 feet from the transition duct connection to the outlet terminal, and the code’s table deducts 2 feet 6 inches per 45 degree elbow and 5 feet per 90 degree elbow. It must terminate outside, at least 3 feet from openings including ventilated soffits, with a backdraft damper and no screen.

Manufacturers publish their own charts, and the binding limit is whichever is shorter. Whirlpool’s installation instructions allow only a 4 inch heavy metal vent with clamps, say plastic or metal foil vent must not be used, prohibit fasteners that extend into the duct interior, and tell you not to use duct tape on the joints. The same document caps flexible metal duct at 7 and three quarter feet. Whirlpool’s venting specification rejects PVC because the pipe wall does not retain heat as well as metal, so condensation forms more easily. GE allows nothing but a 4 inch round duct, limits UL listed semi rigid and foil duct to 8 feet, and says never install a screen or grid in or over the exhaust duct.

Number of 90 degree elbows	Whirlpool maximum rigid metal run, box or louvered hood	Whirlpool maximum rigid metal run, angled hood
None	64 feet	58 feet
One	54 feet	48 feet
Two	44 feet	38 feet
Three	35 feet	29 feet
Four	27 feet	21 feet

Those figures run longer than the code allows, so the 35 foot limit governs where it has been adopted. LG allows 65 feet of rigid metal with no elbows, deducting 6 feet per elbow, capped at four. The Department of Energy tells installers to keep the run short and straight and to fit a booster fan above 35 feet, and warns that long runs and excessive bends create a fire hazard and increase dry time.

Lint, fire and the national figures

The reason the code and the manuals are strict is in the fire data. The US Fire Administration reported an estimated 2,900 clothes dryer fires in residential buildings each year from 2008 to 2010, with an annual average of 5 deaths, 100 injuries and $35 million in property loss.

The cause is maintenance rather than defect. Failure to clean accounted for 34 percent of the contributing factors in that report, the largest single share, and the agency’s current appliance fire page puts it at 31 percent using National Fire Incident Reporting System data for 2018 to 2020. Dust, fiber and lint were the item first ignited in 28 percent of those fires and clothing not on a person in 27 percent.

CPSC investigation work points at the same two places. In its review of investigated incidents, the duct or venting system was the most frequently reported location of origin and the lint trap was second. The commission concluded that lint accumulation in the air flow system reduces airflow and causes internal temperatures to rise.

The US Fire Administration’s own guidance follows from that: never run the dryer without a lint filter, clean the filter before and after each cycle, clean behind the dryer, inspect the venting for damage, crushing or restriction, and confirm the outdoor vent covering opens while the dryer runs.

Gas dryers, blocked vents and carbon monoxide

A gas dryer carries a hazard an electric one does not. Its exhaust contains combustion products, and the duct is the only thing removing them from the house. HUD’s NSPIRE inspection standard gives the purpose directly: remove combustion gases, including carbon monoxide, along with heated air, moisture and lint.

HUD also grades the failures, which gives an owner a ranking. A detached or missing transition duct, restricted airflow from a crushed or kinked duct or an improvised filter over the outlet, and a duct not made of metal or another approved material are each life threatening, with a 24 hour correction timeframe. A missing exterior cover is advisory.

CPSC reports that more than 200 people in the United States die every year from accidental non fire carbon monoxide poisoning associated with consumer products, and recommends alarms on every level of the home and outside sleeping areas. A gas dryer is a reason to get carbon monoxide detector placement right throughout the house, and a reason to treat a blocked vent as urgent rather than annoying.

When to stop and call a professional

Stop at the gas line. The burner assembly, igniter, gas valve and sensor sit behind a panel with a live gas connection, and Whirlpool, GE and Samsung all route that work to a technician. Never run a gas dryer with the vent disconnected or blocked, not even for one load: the exhaust route for combustion gases is gone, and HUD classifies that condition as life threatening.

Stop at the 240 volt circuit as well. Resetting a breaker is an owner’s job. Opening the cabinet to test a heating element, thermal fuse or high limit thermostat means working inside a machine fed by a 30 amp 240 volt supply, and Whirlpool and Samsung both send owners to a technician.

Stop immediately on a burning smell. Unplug the dryer or switch off its breaker, do not restart it to see whether it happens again, and do not add another load. Treat a scorched duct, soot around the vent hood, or a burner that lights and drops out repeatedly the same way. Never fit foil accordion duct as a permanent run, and never use screws that project into the duct: both hold lint where the air is hottest.

Duct work buried in a wall is worth handing over too. LG tells you to contact a specialist if the ductwork is too long or has too many bends, and the Department of Energy’s answer to a run over 35 feet is a booster fan, which is an installation rather than a cleaning. This post quotes no repair price range, because no primary source located publishes a dated US figure.

Frequently asked questions

Can a tripped breaker let the dryer tumble but not heat?

Yes, and on electric machines it is the most common cause. Whirlpool states that one breaker operates the motor and the other the heating element, and that the dryer may not heat if one is tripped. Frigidaire says that if one of the two house circuits or fuses is tripped or blown, the drum may turn but the heater will not operate. Switch the breaker fully off and back on.

How do you tell whether the vent is blocked without taking it apart?

Use the machine’s own test. A Samsung dryer runs a vent blockage test on an empty drum for about two minutes and reports 0 or End for a clear duct, C8 or C80 for about 80 percent clogged, and C9 or C90 for about 90 percent. LG reports d90 for about 90 percent blockage and d95 for about 95 percent.

Is foil accordion duct ever allowed?

Not for the run inside the wall. The code requires a smooth interior duct of metal at least 0.0157 inch thick, which rules out ribbed foil. Whirlpool says plastic or metal foil vent must not be used, and the Department of Energy lists vinyl, nylon, foil and PVC as materials that void the warranty of most dryers. GE allows UL listed foil only for a transition run of 8 feet or less.

How long can a dryer vent be?

The code limit is 35 feet of developed length, minus 5 feet per 90 degree elbow and 2 feet 6 inches per 45 degree elbow. Manufacturer charts run longer: Whirlpool allows 64 feet of rigid metal with no elbows behind a box hood, and LG allows 65 feet. Use whichever figure is shorter.

How often does the vent actually need cleaning?

Whirlpool recommends cleaning the venting from the dryer to the outside every one to two years, sooner if performance has dropped. The lint screen is separate: the US Fire Administration says clean it before and after each cycle, and Whirlpool adds a deep clean with soap, water and a nylon brush every six months.

The split at the top of this post is the whole diagnostic. A cold drum means the heat source is off, and that is usually a breaker or a gas valve you can check in two minutes. A warm drum with damp clothes means the air is not moving, and the answer is a filter, a duct or a hood. That venting work is also what keeps the first fault from turning into a fire.

Dryer Not Heating and Slow Drying Are Two Different Faults