Two jobs, and most people only know about one of them
Looking after a split system is two separate things. Cleaning it, which you do once or twice a year, and keeping it clean, which happens on its own once it is set up. Nearly everyone does the first one and skips the second, which is why the smell always comes back.
Job one: cleaning it
Your filter is the flat mesh panel you slide out of the front. Rinsing it is worth doing, but it is not where the problem is. Past the filter are the coils and the drain tray, and that is where mould and bacteria actually grow, because it is dark and it stays damp for hours after the unit shuts off. A filter rinse never touches it.
A proper clean means getting the chemical onto the coils and flushing what comes off into a catchment bag rather than down your wall. That is the entire job. It takes about twenty minutes a unit.
- Turn the unit off at the wall.
- Hang the catchment bag under the unit so the run-off has somewhere to go.
- Take the filter out and rinse it.
- Spray the coils with the cleaning solution and let it sit while it lifts the build-up.
- Flush it through with the pump bottle. What comes out is the part people photograph.
- Wipe down, put the filter back, close it up, let it dry.
You keep the kit. The next clean, and the one after that, cost you nothing but a refill of solution.
Job two: keeping it clean
This is the part almost nobody does. A gel pot sits behind the filter and evaporates slowly into the airflow, reducing airborne mould and bacteria continuously while the unit runs. No power, no tools, no spray, nothing to remember.
- Cut across the sealed nipple at the end of the packet.
- Open the front of the unit and take the filter out.
- Sit the gel pot behind the filter.
- Put the filter back and close it up.
That is about thirty seconds, and it runs for 10 to 12 weeks.
How many pots do I need?
One per indoor unit. Each pot is rated to 40 to 50m², which is roughly one room, so a pot in the lounge does nothing for the bedrooms. If your house has four heads and you buy one pot, three rooms carry on exactly as they were. Four pots is $96 instead of $120.
Do I need to be handy?
For the gel, no. If you can slide a filter out, you can fit it. For the clean, you need to be willing to open the front cover of the unit, which is a clip or two and no tools on most models. As one reviewer of a competing kit put it, "I have no trade qualifications and followed the instructions, it was easy."
What you should not do is use a kit on a unit with an electrical fault, a refrigerant leak, or damage. That is a technician's job and no amount of cleaning fixes it.