Disclaimer of opinion: This is not normal chemical cleaning, this is a full overhaul whereby your entire unit would be taken down to be cleaned with chemical thoroughly.
Benefits of General Chemical Overhaul :
1) Improves air quality.
2) Extends life span of your Air-conditioner.
3) Saves Electricity.
4) Improves performance and reduce condensation .
5) Air-conditioner more energy efficient .
6) This helps you avoid costly air-conditioner repairs … etc
** Service your air-conditioner regularly to keep it running efficiently. **