Repair or Replace? When Your Old Adelaide Aircon Is Past Saving

The honest answer for most Adelaide aircon repair-vs-replace calls is the 50% rule: if the repair quote is more than half the replacement quote, replace it. That rule holds especially firm once a unit passes eight years old, when the next failure is rarely far behind. This article walks through the four numbers that drive the decision — repair cost, replacement cost, age, and refrigerant type — and shows the actual decision tree on a typical Adelaide example: a 12-year-old Daikin ducted with a TXV failure, $2,400 to repair, $11,800 to replace.

The aim isn’t to push replacement on every reader. Plenty of mid-life Adelaide aircons have years of useful life ahead of them and a $400 repair is the right call. The aim is to help you read your repair quote with the maths in hand, so you don’t sink $2,000 into a system that fails again next summer.

The 50% rule — the simplest decision filter

The repair-or-replace shorthand used across the trade for decades:

If the repair cost exceeds 50% of replacement cost, replace.

Why 50%? Because aircons fail in clusters. Once one major component goes — TXV, compressor, evaporator coil, refrigerant leak in the line set — the next failure is statistically more likely than on a healthy unit, especially past 8 years old. Sinking $2,500 into a $5,000 unit at year 11 of its life and watching the compressor die at year 13 is a familiar story.

Worked through on a real Adelaide unit:

Scenario	Repair quote	Replacement quote	Repair %	Decision
6-year-old Daikin Cora 5kW, faulty fan motor	$480	$2,800	17%	Repair
9-year-old Mitsubishi MSZ-AP 7kW, refrigerant leak	$1,100	$3,200	34%	Repair (borderline — see age below)
12-year-old Fujitsu ducted 14kW, TXV failure	$2,400	$11,800	20%	Replace (age multiplier — see below)
14-year-old Brivis ducted gas, heat exchanger crack	$1,950	$7,600	26%	Replace (safety + age)
8-year-old Samsung 5kW, control PCB	$620	$2,600	24%	Repair
11-year-old Daikin US7 5kW, compressor failure	$1,800	$3,400	53%	Replace

The 50% rule is a starting filter, not the whole answer. Two more factors swing the decision: age and refrigerant type.

Age multiplier — every year past 8 changes the maths

For a 5-year-old unit, the 50% threshold is the right call. For a 12-year-old unit, the threshold drops to 30-35% — because remaining useful life is short and the next failure is closer. The crude age multiplier we use:

Unit age	Repair-cost threshold (% of replacement)
0-5 years	70% (still under manufacturer warranty for many brands)
6-8 years	50%
9-11 years	35%
12+ years	25%

Past 12 years, even a moderate-cost repair is rarely the right call. The compressor — the most expensive component to replace and the one most likely to fail next — has a typical useful life of 10-15 years in Adelaide’s run-hour climate. A 12-year-old unit with one failure already on the books is on borrowed time. The Choice consumer body’s home appliances reliability research tracks aircon failure-rate by age across major brands.

Refrigerant matters: R22 system from 2008 → almost always replace

A separate red flag overrides the standard maths: refrigerant type. If your ducted system was installed before late 2010, there’s a good chance it runs R22 — a refrigerant in advanced phase-out across Australia.

R22 implications in 2026:

• Wholesale price climbed roughly 8x between 2018 and 2026 as supply tightened
• A regas job that cost $400 in 2018 now runs $1,400-$2,200 for a typical 14kW ducted system
• Drop-in replacements (R407C, R422D) work in some systems but lose 8-15% efficiency and frequently void any remaining warranty
• Future regassing will get more expensive each year through the phase-out window

If your ducted unit is on R22 and the failure involves anywhere in the refrigerant circuit — line set, evaporator coil, compressor — the practical answer is replacement. The full picture is in the R22 refrigerant phase-out guide for Modbury and Tea Tree Gully ducted owners, where the 1980s housing stock means R22 systems are particularly common.

You can identify R22 by checking the rating plate on the outdoor unit — refrigerant type is listed as R22, R-22, or HCFC-22.

The five repairs worth doing on a 5-10 year old unit

These repairs hold up the maths and are routinely worth the spend:

1. Capacitor replacement ($180-$320). Common failure, simple swap, restores full function. A capacitor failure left untreated stresses the compressor and shortens its life — fix it.
2. Fan motor replacement ($380-$680). Indoor or outdoor fan. Cheap parts, modest labour. New motor often outlasts the rest of the unit.
3. Control board (PCB) replacement ($420-$780). Modern inverter PCBs do fail. If diagnostic confirms the PCB rather than the compressor or coil, the swap is worth doing.
4. Refrigerant leak repair on R32 systems ($580-$1,200 including regas). A pinhole leak in a brazed joint, fixed and recharged, is sound on a unit under 10 years old.
5. Service / clean / rebalance ($280-$420). Sometimes the unit isn’t broken — it’s just clogged. A proper service restores performance to within 10% of new for a unit that hasn’t been touched in 5 years.

These five repairs are the bread-and-butter of the Adelaide aircon repairs service.

The five repairs that signal the end is near

When the diagnostic comes back as one of these, replacement is almost always the cheaper long-term answer:

1. Compressor failure ($1,800-$3,500 to replace). The most expensive single component, the hardest to swap, and the one most likely to be followed by another failure within 2-3 years.
2. Evaporator coil leak ($1,400-$2,800). The indoor coil leaks because corrosion has set in. The unit is telling you the rest of the system is approaching the same fate.
3. Refrigerant leak you can’t locate ($1,200+ in trace-and-test labour, plus regas, plus the leak still might recur). On units past 9 years old, an unfindable leak is the system asking for retirement.
4. Multiple simultaneous failures ($1,500+). Capacitor, contactor, control board all failing in one service visit means the next thing to die is unpredictable.
5. Heat exchanger crack on gas ducted ($1,800-$2,400). Combustion safety issue — the unit is unsafe to run until repaired, and at this cost on a 10+ year-old gas furnace, replacement is the call.

Energy efficiency gap — old 2-star vs new 5-star running cost over 10 years

The replacement maths often improves once running cost is factored in. A representative comparison for a 14kW ducted reverse-cycle in a 4-bedroom Burnside home:

Metric	2010-era 2-star ducted	2026 5-star inverter ducted
Cooling EER	2.5	3.8
Heating COP	2.8	4.2
Annual electricity	~3,800 kWh	~2,400 kWh
Annual running cost (38c/kWh)	$1,444	$912
Saving	—	$532/year

Over a 12-year unit life, that’s $6,384 in running-cost savings — substantially more than the difference between a $2,400 repair and a full replacement. Add the federal STC rebate ($500-$900 on a ducted reverse-cycle in 2026, claimed at quote stage) and the SA-government rebates flagged in SA rebates for energy-efficient aircon, and the replacement case strengthens further. Energy.gov.au’s running-cost guidance walks through the federal-level efficiency comparison.

The same heat-pump efficiency logic that drives this aircon decision applies to home heating more broadly — and to pool heating. For pool households making the heat-pump-vs-gas call, the running-cost arithmetic at Pool and Spa Quotes’ pool heating cost guide follows the same COP-and-tariff logic.

The hidden cost of a “cheap repair” that fails 8 months later

The trap most homeowners fall into is the $400 capacitor swap on a 13-year-old unit, which keeps the system limping for one more summer before the compressor dies in February — at which point the real replacement happens anyway, but in the wrong window (peak summer pricing, longer install lead-times, often without time to compare quotes properly).

If your unit is 11+ years old and you’re sitting in front of a $400 repair quote, the honest question to ask is: will this unit still be working in 18 months? If the answer is “probably not”, paying $400 to defer the inevitable replacement by one summer often loses money — both on the wasted repair and on the higher peak-season replacement cost. The cheapest replacement window is autumn (April-May), as covered in off-season install discounts. Forced February replacements pay 15-20% more.

Sample decision tree: 12-year-old Daikin ducted with TXV failure

A real recent example from a Modbury household:

• System: 14kW Daikin ducted reverse-cycle, installed 2014, R410A
• Failure: thermostatic expansion valve (TXV) on the evaporator coil. System runs but cooling output collapsed. Diagnostic confirmed TXV.
• Repair quote: $2,400 (TXV part, labour, recover and recharge refrigerant, performance retest)
• Replacement quote: $11,800 for an equivalent 14kW Daikin Premium Inverter ducted reverse-cycle, post-rebate

The decision filter:

1. Repair %: 2400 / 11800 = 20%. Below 50% rule threshold.
2. Age: 12 years. Triggers age multiplier — threshold drops to 25%.
3. At 12 years old, 20% repair cost is borderline under the age-adjusted threshold. The 50% rule alone says repair; the age multiplier says it’s marginal.
4. Refrigerant: R410A. Not R22, no phase-out flag.
5. Energy gap: old 2.7-star unit vs new 5-star = ~$540/year running-cost saving. Over remaining unit life (3-5 years optimistic), that’s $1,600-$2,700 saved.
6. Compressor risk: 12-year-old compressor under stress. Statistical odds of compressor failure within 3 years ~35%.

The call: replace. The repair is below the headline 50% threshold, but at year 12 the math tilts on the age multiplier, the running-cost gap, and the elevated compressor-failure probability. Spending $2,400 to defer a $11,800 decision by 2-3 years lost the household roughly $1,600 in running cost and committed to another $1,800-$3,500 compressor exposure. The household replaced. Their new ducted system, with the STC rebate applied, ran $11,200 — the ACL warranty rights are detailed here. The ACCC’s consumer guarantees on appliance repairs and replacements underpins the legal framework.

When you get a written quote — what to ask for

For an aging system facing a major repair, the smart play is to get a repair quote AND a replacement quote in the same visit. When you request a written quote from us, asking for both lets you run the maths cleanly:

• Confirm the repair cost in writing, with the part identified
• Confirm the replacement cost in writing, with the system class and brand specified
• Ask for the age-multiplier read — we see fail-frequency data daily
• Ask whether federal STC rebate is applied at quote stage and the indicative amount
• Ask whether the old unit’s refrigerant recovery and disposal is included (it should be — federal Ozone Protection law)

A repair quote and a replacement quote, side by side and both in writing, gives you the genuine read on which way the maths falls.

Frequently asked questions

What’s the typical lifespan of an aircon in Adelaide?

Twelve to fifteen years for a well-installed reverse-cycle split, ten to thirteen years for a ducted reverse-cycle, eight to twelve years for evaporative coolers. Coastal-rated splits at Glenelg or Henley Beach without proper coil protection often fail at year seven or eight from salt-spray corrosion. Adelaide’s run hours are punishing — assume the lower end of the brand-quoted range.

When is an aircon repair not worth doing?

When the repair quote is over 50% of the replacement quote and the unit is past 8 years old. When the failure is in the compressor or the evaporator coil itself. When the system runs R22 refrigerant (pre-2010 ducted) and the leak is anywhere in the line set. Any one of those three triggers a strong replace recommendation.

Should I replace my pre-2010 R22 ducted system now?

Yes — and the longer you wait, the worse the maths get. R22 wholesale price has climbed roughly 8x since 2018 and supply is genuinely tight in 2026. A regas job that cost $400 in 2018 now runs $1,400-$2,200. The full picture is in our R22 phase-out guide.

How much will I save on running costs by replacing an old unit?

A 2-star ducted from 2010 typically draws 30-50% more electricity than a 2026 5-star inverter at the same output. For a $1,200/year ducted running cost on the old unit, the new unit lands around $720-$840 — saving $360-$480 a year. Over a 12-year unit life, that’s roughly $5,000 in running-cost savings, before any rebate or comfort improvement.

Is it worth replacing just the outdoor unit?

Almost never on a system over 8 years old. Indoor and outdoor units are matched as a pair for refrigerant charge, oil compatibility, and control electronics. Mismatched pairs lose 15-25% efficiency and most manufacturer warranties. The exception is identical-model swap inside the warranty period for an isolated condenser failure.

Can I trade in my old aircon when buying a new one?

Yes — and federal Ozone Protection law actually requires the installer to recover and dispose of the old refrigerant properly, so removal is built into the install quote anyway. Genuine trade-in credit is rare ($50-$150 token allowance), but proper disposal is non-negotiable. Confirm it’s listed as included on the quote.

Ready for a written, line-itemed Adelaide repair-or-replace quote?

Submit the quote form — we’ll be in touch within 24–48 hours, providing both the repair cost and the replacement cost so you can run the 50% rule on real numbers.