What Actually Happens During an Aircon Chemical Wash
Chemical wash gets recommended often — sometimes correctly, sometimes not. If you know what the process actually does, you can make a more informed decision about whether your unit needs it.
What a Chemical Wash Involves
A chemical wash is a coil cleaning process. The technician dismantles the indoor unit more extensively than in a general service — removing the front casing and pulling out the evaporator coil for direct cleaning.
A chemical cleaning solution is applied to the coil to dissolve accumulated grime, mould, and bio-film that normal servicing cannot shift. The coil is then rinsed thoroughly, dried, and reinstalled.
The drain pan, fan barrel, and internal housing are also cleaned as part of the process. The result is a unit that is cleaner on the inside than a general service can achieve.
How It Differs From a General Service
A general service cleans what is accessible without dismantling the unit — the filter, the surface of the coil, the drain line, and the outer casing. It handles normal dust and light buildup from regular use.
A chemical wash goes deeper. The coil comes out, the cleaning solution reaches places that cannot be reached during a general service, and the level of clean is significantly higher.
The trade-off is time and cost. A chemical wash takes longer, involves more disassembly, and costs more than a general service. It is not a better version of the same thing — it is a different procedure for a different problem.
| What Gets Done | General Service | Chemical Wash |
|---|---|---|
| Filter cleaned | Yes | Yes |
| Coil surface wiped | Yes | Yes, plus chemical soak |
| Coil fully removed and cleaned | No | Yes |
| Fan barrel cleaned | Partial | Full |
| Drain pan cleaned | Partial | Full |
| Time required | Shorter | Longer |
When a Chemical Wash Is the Right Call
A chemical wash is appropriate when a unit has not been serviced regularly and has accumulated buildup that a general service cannot clear. Common signs include persistent musty smell after servicing, weak cooling that does not improve after a general service, or visible mould growth on the fan barrel or coil.
Units that have gone a long time without servicing often need a chemical wash as a reset before returning to a regular service schedule.
If your unit has been serviced on a consistent schedule and is performing well, a chemical wash is not needed. A general service is sufficient.
When a Chemical Wash Is Not the Right Call
A chemical wash will not fix a refrigerant leak, a faulty fan motor, a failing compressor, or a blocked drain float switch. These are mechanical faults that require diagnosis, not cleaning.
If your unit is not cooling and someone recommends a chemical wash before checking refrigerant pressure and airflow, ask for the diagnostic reasoning. Cleaning cannot fix a gas loss or a failing component.
A chemical wash also does not replace the need for ongoing regular servicing. Doing a deep clean and then not servicing again will simply rebuild the same grime over time.
What To Expect During the Visit
The technician will shut off the unit and power. The indoor unit is then dismantled more extensively than in a general service. Expect the process to take noticeably longer than a standard visit.
The coil cleaning involves chemicals that should not come into contact with your furnishings. A technician will lay down coverings before the process begins. Make sure the area is cleared before the visit.
After the chemical wash is complete, the unit will be reassembled and run to verify it is working correctly. You should expect normal cooling to return. If cooling is still weak after a chemical wash, the issue is not clean-related — it is a system fault.