A dryer can tumble normally while the heating circuit is disabled.
Start Here
Confirm correct power supply.
Clean lint screen.
Inspect exhaust airflow.
Check settings and energy-saving modes.
Consider thermal fuse, heater or gas ignition only after airflow checks.
Appliances rarely fail in a way that names the defective component for you. A dryer can tumble normally while the heating circuit is disabled. For dryer runs but does not heat, concentrate on heat, drum movement and unrestricted airflow. Use every working function as evidence: if one stage still behaves normally, that fact eliminates causes that would have stopped the appliance earlier in the sequence.
Observe the timing before touching anything. Note what happens immediately after Start, what changes just before the fault, and what remains normal afterward. Lights, relay clicks, water movement, motor or fan sounds, heat, vibration and error codes are useful only when tied to a point in the cycle. A fault that appears instantly is a different problem from one that appears only after the machine warms up or reaches a later stage.
Begin with the cheapest conditions to verify: confirm correct power supply, then clean lint screen. Do not merely glance at them. Compare the actual condition with the manual, correct anything obviously wrong, and retest before moving deeper. Simple installation, maintenance and user-setting problems regularly imitate failed electrical parts.
If those checks pass, move to inspect exhaust airflow. Then decide whether check settings and energy-saving modes can be evaluated safely with power isolated. Choose one test that answers one question: blocked or clear, open or closed, free or jammed, intact or electrically open. If a test result would not change your next decision, the test is probably not worth doing.
Avoid running with a blocked vent, using foil/plastic venting where prohibited, and probing live heater circuits casually. All three skip evidence and can turn a minor fault into an expensive one. After a correction, reassemble guards and connectors, restore normal settings, and reproduce the original operating conditions. A single successful start is not proof; the original symptom must stay gone through the stage that used to fail.
A Safe Step-by-Step Check
Document the exact symptom and pay special attention to confirm correct power supply.
Remove external causes first; specifically verify clean lint screen.
With power isolated where required, inspect inspect exhaust airflow and then evaluate check settings and energy-saving modes only if it can be done safely.
Reassemble fully and run a controlled test under the conditions that previously caused the fault.
Common Beginner Mistakes
Running with a blocked vent.
Using foil/plastic venting where prohibited.
Probing live heater circuits casually.
STOP AND GET HELP: If the next useful test requires exposed live mains, defeating a safety interlock, opening a sealed refrigeration circuit, disturbing gas controls, or entering a microwave high-voltage section, the diagnosis has reached the professional-service boundary.