Begin with the condition, not a calendar
EPA recommends duct cleaning as needed rather than routinely. Substantial visible mold in hard-surface ducts, vermin and excessive dust or debris are reasons to consider cleaning. Ask for observations that relate to your system.
Understand the scope
Ask which components are included and which are excluded. Supply and return ducts, registers and HVAC components are not interchangeable line items. Ask how inaccessible parts will be handled and how work will be documented.
Compare providers carefully
Get written estimates and ask for references. EPA warns against sweeping health claims and notes that it does not certify duct cleaning companies. A claim of “EPA certification” is not evidence of provider competence.
Make causes part of the conversation
If moisture or contamination is found, ask what needs correcting before cleaning. Otherwise the concern may recur. Understand any proposed chemicals or sealants before agreeing to them.
Keep expectations realistic
Duct cleaning has not been shown to prevent health problems. This independent guide does not assess your home or refer to a confirmed service partner. It helps you prepare questions for a provider you choose.