Dryer Not Heating — The Complete Diagnostic Guide for Every Machine Type

The First Thing to Understand — Heat and Airflow Are Both Required

A dryer needs two things to dry clothes: heat to evaporate moisture from fabric, and airflow to carry that moist air out through the vent. When either is absent or inadequate, clothes come out damp. This distinction matters because some apparent no-heat symptoms are actually restricted airflow — the heat is present but cannot work efficiently because the exhaust is blocked.

Before beginning any component-level diagnosis, confirm that the machine is actually producing no heat — not just drying slowly. Reach inside the drum two minutes into a cycle. If there is warmth but clothes are still damp after a full cycle, the issue may be airflow restriction rather than a failed heating component. True no-heat is a drum that is cold after five or more minutes of operation.

Electric Dryer — No Heat Diagnostic Sequence

Step 1 — Check the Circuit Breaker

Electric dryers run on a dedicated 240-volt circuit using two separate 120-volt breakers wired together. These two breakers can trip independently. When only one trips, the dryer receives 120 volts — enough to run the drum and motor, not enough to power the heating element. The machine tumbles with no heat. From the outside it looks like a heating failure. From the electrical panel it is a tripped breaker.

Go to the electrical panel. Find the dryer breaker — a double-width unit. Push it firmly to the full off position, then back to on. Do not just check whether it looks tripped — reset it deliberately. Test the dryer. If the breaker trips again immediately, there is an electrical fault in the machine or circuit that requires professional diagnosis.

Step 2 — Test the Thermal Fuse

The thermal fuse is the most common single cause of electric dryer no-heat. It is a one-time-use safety device that permanently opens the heating circuit when temperature exceeds the rated threshold. Once blown it must be physically replaced — there is no resetting it.

The thermal fuse is tested with a multimeter set to continuity or resistance. With the dryer unplugged, the fuse is accessed — typically located on or near the heating element housing — and tested. A functioning fuse shows continuity. A blown fuse shows no continuity. This test is definitive.

Critical point: replacing the thermal fuse without identifying and fixing the root cause means the new fuse will blow under the same conditions. The root cause is almost always a restricted vent system — seized exterior vent cap, crushed transition duct, lint-blocked in-wall duct, or duct run over the code maximum. Inspect the full vent system every time a thermal fuse is replaced.

Step 3 — Test the Heating Element

The heating element is a coil of high-resistance wire that heats when current passes through it. When the element coil breaks — from fatigue, mineral scale accumulation, or simple age — the circuit opens and the element produces no heat. Testing with a multimeter: the element should show resistance (not open circuit). A reading of infinite resistance or OL indicates a broken element.

Visual inspection also helps — a broken element coil is sometimes visible as a gap or burn mark in the wire. On machines in hard-water areas, the element may also show mineral scale deposits on its surface, which insulate the element and cause it to run hotter than designed before eventually failing.

Step 4 — Test the Cycling Thermostat

The cycling thermostat regulates drum temperature by switching the heating element on and off. A thermostat that has failed open permanently cuts power to the heating element — the machine produces no heat even though the fuse and element are intact. Testing: the cycling thermostat should show continuity at room temperature. No continuity at room temperature indicates a failed thermostat.

Step 5 — Test the High-Limit Thermostat

The high-limit thermostat is a secondary safety device between the cycling thermostat and the thermal fuse. When it fails open, it cuts the heating circuit. Same test as the cycling thermostat — continuity at room temperature. Some high-limit thermostats are designed to be manually resettable; if there is a small button on the thermostat body, press it and test again before condemning the part.

Step 6 — Check the Control Board

On modern electronic dryers — particularly Samsung, LG, and current Whirlpool and Maytag — a failed control board can prevent the heating relay from energising even when all heating components are functional. This is the last item in the sequence because it is the most expensive and least common. Control board failure is diagnosed by elimination — when all upstream components test correctly and the machine still produces no heat, the board is the remaining suspect.

Gas Dryer — No Heat Diagnostic Sequence

Gas dryers share the same vent system, cycling thermostat, high-limit thermostat, and thermal fuse as electric machines — these should be checked with the same methods and in the same order. But the heating system itself is completely different and requires a separate diagnostic sequence.

Step 1 — Confirm Gas Supply

Before opening the machine, confirm the gas supply valve behind the dryer is fully open and that other gas appliances in the house are working normally. A closed or partially closed supply valve produces no heat and is sometimes the entire explanation. Also confirm the gas type — natural gas vs propane — and that the machine is configured for the fuel being supplied.

Step 2 — Test the Thermal Fuse

Same as on an electric machine — same test, same importance, same warning about addressing the root cause before replacing the fuse.

Step 3 — Test the Igniter

The igniter is the most commonly replaced component on gas dryer no-heat calls. It is a silicon carbide element that heats to glowing orange to ignite the gas burner. When the igniter fails — typically by cracking — it produces no glow and the gas valve never opens.

Visual inspection during operation: with the machine running and the burner area visible, the igniter should glow orange within the first 30 to 60 seconds of the cycle. No glow indicates igniter failure. The igniter can also be tested with a multimeter — it should show resistance in the range of 50 to 400 ohms depending on the model. An open circuit reading confirms failure.

Step 4 — Test the Gas Valve Coils

The gas valve is held closed by spring tension and opened by electromagnetic coils energised when the igniter reaches operating temperature. When the coils fail — either the primary coil, the secondary coil, or both — the valve remains closed even when the igniter glows correctly. The symptom: the igniter glows, then turns off, but no flame appears. This cycle repeats every 60 to 90 seconds.

Gas valve coils are tested with a multimeter for continuity and resistance. A failed coil typically shows open circuit or significantly out-of-spec resistance. Coil sets are usually replaced as a unit rather than individually.

Step 5 — Test the Cycling and High-Limit Thermostats

Same tests as electric — continuity at room temperature. On gas dryers, a failed cycling thermostat prevents the gas valve from receiving the signal to open, even when the igniter is functional. A failed high-limit thermostat has the same effect.

Step 6 — Check the Radiant Sensor

Some gas dryer designs include a radiant or flame sensor that monitors whether the burner flame is established after ignition. A failed radiant sensor causes the gas valve to close immediately after the flame lights — producing a machine that briefly ignites and then shuts off, repeating on a short cycle. This produces heat intermittently but never sustained heat. If the machine produces brief bursts of warmth but no sustained heat, the radiant sensor is the primary suspect.

The Vent System — Check This on Every No-Heat Call

Regardless of whether the dryer is electric or gas, the vent system must be assessed on every no-heat call. A restricted vent is the most common root cause of thermal fuse failure — the most common single component failure — and replacing the fuse without clearing the restriction produces a repeat failure within weeks to months.

The vent check takes five minutes and requires no tools: run the dryer, go outside, put your hand in front of the exterior vent cap. Airflow should be strong, warm, and consistent. The louvres or flap should be fully open. Weak airflow or a stuck cap needs to be addressed before the no-heat repair is considered complete.

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