1. Stop at the safety boundary
Do not test combustion appliances by creating strong negative pressure.
2. Capture the baseline
Take one context photo, one close view and a short note describing location, date, weather, recent water use, equipment state and occupancy.
3. Track the trigger
Cooking, hood operation and interior door position.
4. Compare, do not assume
Supports this pathway
- Odor worsens when the hood is off
- Nearby return air picks it up
- Opening a window changes capture
Weakens this pathway
- The odor originates from a drain
- The hood exhausts outdoors with good capture
- Odor persists without cooking
5. Repeat only safe checks
- Observe steam capture at different fan speeds
- Check whether the hood exhausts outside
- Compare door and window positions
6. Decide the next step
If the pattern is active, expanding, safety-related or requires opening inaccessible construction, stop self-help testing and prepare an evidence-based handoff. An HVAC professional should assess capture and make-up air when powerful exhaust is used.
7. Verify the outcome
After any action, repeat the same observation under a comparable trigger. A dry surface immediately after work is not sufficient proof when the original symptom was intermittent.
Observe→Compare triggers→Repair source→Verify outcome
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