In our article “About Chemical Cleaning”, we briefly described the process of fancoil chemical cleaning. However, there are many variations of chemical washing provided by different aircon contractors  at different pricing. The scope of work differs greatly as well as the charges. Let me quote an example. I have seen companies quoting chemical wash for $60. Their scope of work involves the regular aircon servicing scope, plus spraying of chemical solution on the filter and cooling coil. This is their so-called chemical wash. On the other side of the spectrum, local manufacturing agents charge between $180-$230 for their chemical overhaul. By looking at the price differential, you can tell there is something very different with the services provided.

The purpose of this article is not to comment on the different types of chemical cleaning by different aircon companies, but to list the scope of chemical overhaul work which is aligned to the manufacturer’s recommended practice.

Below is the chemical overhaul scope:

  1. Pump down refrigerant gas into condensing unit and lock service valve.
  2. Unsecure flare jointing and disconnect electrical wiring and drain pipe at the fancoil unit.
  3. Dismantle the fancoil unit down from the wall.
  4. Once the fancoil unit is on the ground, proceed to dismantle the electrical circuit board, evaporator coil, drain pan, fan motor and fan blower. Tape up flare opening of evaporator coil.
  5. Brush the electrical circuit board and fan motor surface off dust. Check for any abnormal burnt mark.
  6. The evaporator coil, drain pan, fancoil front cover, fancoil body, fan blower will be chemically washed  in the washing area.
  7. Use alkaline chemical instead of acidic chemical which may be more corrosive.
  8. Flush the above parts with water and inject chemical solution. The chemical solution will react with the water and the dirt to cause a forming process. The forming process will extract dirt trapped deep inside the parts.
  9. After forming process completed, the parts must be thoroughly flushed with water to remove all residual chemical solution.
  10. Wipe dry all parts and reassemble the fancoil unit back.
  11. Clear the drain piping via vacuuming or flushing.
  12. Install the fancoil back at the wall. Secure the flare joint and connect the electrical wiring and drain pipe at fancoil.
  13. Use a vacuum pump to extract out air and foreign material in the refrigerant piping system.
  14. Unsecure the service valve and test for leakage at fancoil flare jointing.
  15. Test run the air conditioner and checks for correct operating pressure.

Above is the detailed description of the chemical overhaul process. Chemical cleaning work must be done properly and correctly in order to maximise the cleaning effect. If carried out incorrectly, corrosion and leakage will occur. In severe cases, damage to the air conditioner system is possible.