How to Clean a Split System Air Conditioner (Step-by-Step)

What You’ll Need

Step 1: Turn Off Power at the Wall and Switchboard

Before touching any part of your split system, turn off the unit at the remote control, then switch off the circuit breaker at your switchboard. Split systems carry 240V mains power to the indoor unit at all times — even in standby mode. Do not rely on the remote control alone to de-energise the unit.

Step 2: Remove and Wash the Filters

Lift the front panel of the indoor unit by pulling the bottom edge forward and upward — on most Daikin, Mitsubishi, Panasonic, Fujitsu, and Actron units, the panel hinges at the top and locks open. Slide the mesh filters straight out toward you.

• Rinse filters under a cold tap — never hot water, which can warp the plastic mesh frame
• Use a soft brush and mild dishwashing liquid for heavy dust build-up
• Shake off excess water and allow to air-dry completely before reinstalling — do not refit wet filters
• In Melbourne’s dusty SE suburbs (particularly Officer, Pakenham, Cranbourne which have agricultural dust), filters may need fortnightly cleaning during autumn

Step 3: Clean the Indoor Unit Body and Vanes

With the filters removed, wipe down the interior plastic housing with a barely damp microfibre cloth. Do not use abrasive cleaners or spray liquids directly into the unit. Pay particular attention to:

• The horizontal vanes (louvres): These accumulate dust and biofilm. Wipe each blade with a damp cloth folded thin enough to reach between them.
• The vertical vanes: Usually harder to reach — use a soft brush or pipe cleaner for the gaps.
• The drain tray: Located below the evaporator coil. This should be damp but not have standing water. Algae or mould growth in the drain tray indicates a partially blocked drain line (see Troubleshooting).

Step 4: Apply Coil Cleaner (Annual Deep Clean)

Once a year — ideally October before summer heat — apply a foaming coil cleaner to the evaporator coil (the fins visible behind the filter rack). Self-rinsing coil cleaners from brands like Air Con Cleaner or Chemours are designed to foam, penetrate the fin pack, and drain out through the condensate line without rinsing required.

1. Protect the wall and any nearby electrical outlets with plastic sheeting or taped newspaper
2. Shake the can and apply foam evenly across the coil face — work top to bottom, left to right
3. Allow the foam to dwell for 5–10 minutes (read product instructions)
4. The foam will dissolve and drain through the condensate outlet — ensure the drain line is clear first (see Troubleshooting)
5. Reinstall dry filters and restore power

Step 5: Check the Outdoor Unit

The outdoor condenser unit also needs attention annually. This is more straightforward — no foaming cleaners needed for basic maintenance:

• Clear leaves, grass, and debris from around the unit — leave at least 500mm clearance on all sides
• Hose down the coil fins with a gentle stream (low pressure) from the inside-out direction if possible, or carefully from outside — avoid bending the fins
• Check that the unit is level and that vibration mounts are intact
• Do not clean the electrical cabinet inside the outdoor unit — this requires a licensed HVAC technician

Troubleshooting Table

When to Call a Licensed HVAC Technician

DIY cleaning covers the filters, coil exterior, drain tray, and outdoor condenser fins. Call a licensed HVAC technician for:

• Refrigerant gas top-up or leak check — handling refrigerant requires an ARCtick licence in Australia
• Electrical fault diagnosis — compressor starting issues, PCB faults, communication errors
• Chemical coil clean with full washdown — requires special equipment and drainage management
• Drain line blockages that don’t clear with vacuum and flush
• Any work inside the outdoor unit’s electrical cabinet

In Melbourne’s SE suburbs, HVAC service call-outs typically cost $120–$180 for the first hour. Annual servicing contracts with companies like Brivis, Climate Plus, or local independents run $150–$250 per unit per year.

Tips and Gotchas

1. Clean before summer, not during. A dirty coil on the first hot day of the season means poor cooling exactly when you need it most — and emergency HVAC call-outs in January cost significantly more than planned servicing.
2. Don’t use household spray cleaners inside the unit. Chemicals like Glen 20 or bleach can corrode aluminium fins and plastic components. Use only purpose-made coil cleaners or diluted white vinegar on the drain tray.
3. Some units have a self-clean mode. Daikin, Mitsubishi Electric, and Panasonic all offer auto-clean cycles on premium models that run the fan in reverse to dry the coil. Enable this if your unit has it — it reduces mould growth significantly between manual cleans.
4. Fin damage is easy to cause. The aluminium fins on both indoor and outdoor coils bend easily. Always use low pressure when hosing and never use a screwdriver or sharp tool to clear debris from fins — use a fin comb instead.
5. Pets dramatically increase cleaning frequency. Pet dander and hair clog filters 2–3x faster than a pet-free home. If you have cats or dogs, check filters every 1–2 weeks during summer.
6. The drain line termination point. In most installations, the drain line exits through the wall behind the unit and terminates outside — find this point and check it’s not blocked by a spider web, mud, or vegetation.
7. Log your servicing. Most split systems have a 5–7 year compressor warranty that requires evidence of regular maintenance. Keep a simple service log noting each clean date.

Local Melbourne Resources

• Bunnings — coil cleaner sprays, microfibre cloths, fin combs
• Total Tools — HVAC fin combs, wet/dry vacuums for drain line cleaning
• ARCtick Register — verify your HVAC technician holds the required Australian refrigerant handling licence
• Local HVAC service companies: Climate Plus (Dandenong), Daikin authorised service agents across Melbourne SE

FAQ