Hear the cycle
Sound Lab
Listen for the trigger, not only the noise.
Rhythm, system cycle and strongest location often distinguish movement, flow, vibration and electrical signals.
Describe your clue →Air restriction01
HVAC whistling
A steady high tone that changes with airflow or grille position.
- Trigger
- fan operation
- Strongest location
- register, filter or narrow leakage path
Sensory method
Describe first. Interpret second.
- TriggerWhat changed immediately before it began?
- CycleDoes it follow startup, flow, heating, wind or room use?
- LocationWhere is it strongest, and does that move?
- Stop conditionHeat, smoke, gas or electrical odor changes the response immediately.
