Start with what is actually happening in the system. An assessment, cleaning after renovation and replacement of damaged ducts require different evidence and different scopes.
Have the details ready
What did you notice, and in which room? Was there recent renovation, moisture or pest activity? Where are the filter and air handler, if known?
Describe the concern
Explain visible debris, moisture, pests or recent renovation work. Identify when and where the issue appears.
Look at accessible components
Ask which supply and return sections, registers and air-handler components can be assessed, and which areas cannot be reached.
Agree on an evidence-based scope
Request images tied to component locations and a written explanation of proposed cleaning, repair or referral. A finding should lead to a specific next step.
Keep a record
Keep the agreed scope, itemized invoice and documented findings together for any future visit.
Useful references
EPA · when to consider duct cleaning ↗General guidance. Confirm the scope for your property.