The smell people describe as “the AC smell” is biological. The indoor coil condenses moisture out of the air; that moisture sits in the drain pan and on the blower wheel, and combined with the fine organic dust that gets past a filter it grows a biofilm. Every morning the fan pushes air across that layer and into the room. Washing the filter does nothing about it, because the filter is not where the growth is.
Filter wash vs deep clean
| Item | Filter wash | Deep clean |
|---|---|---|
| Filters | Yes | Yes |
| Indoor coil | No | Foam cleaned and rinsed |
| Blower wheel | No | Removed and washed |
| Drain pan and line | No | Sanitised and flushed |
| Outdoor coil | No | Pressure rinsed |
| Typical time per unit | 10 minutes | 45–60 minutes |
Airflow at the vent, before and after
- Work was done over two nights so no child was in the building during cleaning.
- Coils were sanitised with a product safe for occupied spaces, then fully rinsed.
- Drain lines were re-sloped where water had been standing.
- The nursery moved to a three-month cycle, which is the right interval for rooms with high occupancy and low ceilings.
Questions about this case
How often do nurseries and schools need deep cleaning?
Every three months during the operating year. High occupancy means more moisture and more organic dust than a normal home.
Do you work outside opening hours?
Yes — nurseries, schools and clinics are usually done at night or on weekends so the space is empty and ready in the morning.
Is the cleaning product safe for children?
We use coil cleaners intended for occupied buildings and rinse thoroughly, and the space is ventilated before it is used again.
The same service in your district
AC cleaning & gas refill is available in Al Narjis and every Riyadh district.
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