HVAC Warning Signs to Document

Visible clues to document

Photograph both a close view and a wider view that shows location and scale. Note whether the condition appears active, repeated, recently repaired, or associated with weather or system use.

• Rust, staining, soot, damaged venting, disconnected ducts, or water near equipment.
• Unusual noise, odor, short cycling, weak airflow, or large temperature differences.
• Missing service information, damaged filters, blocked returns, or condensate drainage concerns.

What the clues may—and may not—mean

Similar-looking conditions can have very different causes. Surface appearance alone cannot confirm severity, concealed damage, material composition, structural movement, leakage source, or health risk.

Reasonable next steps

• Leave immediately and contact emergency services or the fuel utility for a gas odor or carbon-monoxide alarm.
• Do not open or repair combustion or electrical compartments.
• Arrange service and any needed combustion-safety or performance testing.

Who to contact

For a property-specific assessment, contact a licensed or qualified HVAC professional; contact the fuel utility or emergency services for suspected gas or combustion danger. Ask for findings in writing and request a defined scope before authorizing invasive testing or repair work.