Most building and pest inspectors check for structural integrity, water damage, and termites. The aircon usually gets a tick if the unit looks present and the previous owner says it works. But a $14,000 aircon system that fails six months after settlement is exactly the kind of hidden cost that catches buyers off guard — and the warning signs are usually visible to anyone who knows what to look for.
Why aircon matters in a pre-purchase inspection
A reverse cycle ducted system installed today costs $14,000 to $22,000. A multi-split is $9,000 to $15,000. Switchboard upgrades that may be needed alongside add another $2,500 to $5,500.
For most buyers, this is the second or third biggest non-structural cost they would face on a property after buying. Knowing the system’s actual condition before settlement matters financially — and unlike termites or roof leaks, aircon condition is rarely covered by insurance later.
What a thorough building inspector checks on the aircon
Outdoor unit (condenser)
- Age — read the data plate. Most condensers last 12-15 years. Anything over 10 is on borrowed time.
- Refrigerant gas type. Older systems on R22 are obsolete; R22 is no longer manufactured in Australia. R32 and R410A are current.
- Visible damage to the casing, fan, fins.
- Position. Is it level? Is the concrete pad cracked? Is it set back appropriately from the boundary?
- Brand. Major Japanese manufacturers (Mitsubishi, Daikin, Fujitsu, Panasonic) and some Korean (LG, Samsung) hold up. Off-brand units have higher early failure rates.
Indoor units
- Visible mould on the louvres or surrounding wall (suggests system has been running with insufficient drainage)
- Water staining on walls or ceilings near indoor units
- Operation noise (rattling indicates worn bearings; whining indicates fan motor issues)
- For ducted: check ceiling vents are present in every room they should be, not blocked or painted over
Electrical and switchboard
- Is there a dedicated circuit for the aircon? (There should be.)
- Is the switchboard original 1970s-era or upgraded? An old switchboard with no RCDs running modern aircon is a safety concern.
- Has the electrical capacity been calculated for the aircon load plus the rest of the home?
Service history
The seller may or may not have records. Ask. Documented annual servicing on a 6-year-old system is reassuring. No service records on a 10-year-old system means the system has likely been running on borrowed time.
What good building inspectors actually do
The best inspectors run the system during the inspection — heat mode in winter, cool mode in summer. They check airflow at every vent, listen to the compressor cycling, and feel for cold/warm air actually reaching the rooms.
This level of practical check is the difference between a thorough pre-purchase report and one that just notes the system “appears present.” Brisbane inspectors like Zoom Building & Pest Inspections include detailed system testing as part of their standard inspection process — and the report shows you exactly what was tested, the result, and any concerns flagged for follow-up.
Questions to ask the seller before settlement
- What year was the aircon installed?
- Who installed it, and is the install paperwork available?
- When was it last serviced, and by whom?
- Has it been topped up with refrigerant gas in the last 5 years? (Frequent top-ups indicate a leak.)
- Are the original purchase receipts and warranty documents available?
Push for documentation. Sellers who cannot produce any of this on a system they say works fine are usually telling you something.
When to walk away vs negotiate
An aircon system at end of life is rarely a deal-breaker on a property purchase. It is, however, leverage during the price negotiation. A $14,000 anticipated replacement cost is a legitimate basis for a price reduction or for walking back from a high offer.
What is more concerning: signs of repeated failure, water damage from previous leaks, or evidence the seller has been hiding the system’s condition. Those raise broader questions about what else might be undisclosed.
The aircon check is rarely the most exciting part of a building inspection. It is sometimes the most expensive one to skip.
