Reconstruct the cleaning visit
Get the invoice, photos, and method used. Ask whether the work included the accessible filters, coil, fan, water collection area, and drain, or whether “deep cleaning” meant something narrower. Ask which products were applied and whether they were approved for this equipment. Do not spray bleach, fragrance, or another cleaner into the head yourself.
Record when the smell occurs: at startup, only in one mode, after the unit has been idle, or whenever air moves through it. Note whether other heads have the same odor and whether the room smells when the system is off. Share any recent leak, renovation, or other moisture event. These observations help direct inspection; they do not establish contamination.
Look beyond the visible surface
We would ask the technician to inspect the actual odor source and check whether the unit and its drain are functioning as intended. Have them distinguish residue or remaining contamination inside the equipment from a moisture source in nearby wall or ceiling materials, or an odor entering from elsewhere in the room.
If the investigation points to wet or contaminated building materials, ask a qualified moisture or remediation provider to assess that part of the problem. Have the providers identify who owns equipment work, building cleanup, and drying. Ask for photos and findings rather than a broad statement that “mold is everywhere.”
Our recommendation changes when a source is identified. Cleaning may be appropriate, a drainage repair may be needed, or the room itself may need work. We would want a plan for removing the source and preventing recurrence, with a follow-up observation period and clear criteria for a return visit.
Your next step: Request a targeted odor and moisture investigation with the previous cleaning record. Ask what evidence supports the proposed correction before agreeing to another treatment.