For most Sydney homes, once a year is the right cadence, ideally booked in spring before the first heatwave. Some situations bump that up to twice a year. A small number push to quarterly. Almost no system genuinely benefits from less than annual servicing, regardless of how lightly it’s used.

Here’s how to work out which category your system falls into and the best time of year to actually book it in.

The baseline: annual servicing for most homes

Most manufacturers and reputable installers settle on annual as the minimum cadence for a residential system. The reason is that the things a service catches (clogged filters, dirty coils, blocked drains, slowly leaking refrigerant, aging electrical components) accumulate over a season of use and start affecting performance and reliability if left for longer.

A typical residential service runs $150 to $300 for a split system and $250 to $400 for a ducted system. The cost-of-doing-nothing maths usually works out badly: a serviced system is roughly 15 to 20% more efficient than a neglected one, which is a few hundred dollars a year on the power bill of a typical Sydney home. Add in the avoided cost of premature compressor failure ($1,500 to $3,000+) and the case writes itself.

When to book it

Timing matters more than people realise.

September and October is the sweet spot for most Sydney homes. The system has been mostly idle through winter (or running heating, depending on use), the technician diary has actual capacity, and any issues get sorted before the first 35°C+ day of the season hits.

Early November still works but demand is climbing. Bookings are a couple of weeks out by this point in most years.

December through February is the worst possible time. Every aircon company in Sydney is booked out for emergency repairs, technician availability is measured in weeks, and the cost of a callout if something goes wrong is significantly higher.

March and April is a reasonable backup if you missed the spring window. The system has worked hard through summer and a service before winter heating use isn’t a bad idea.

The pattern that works for most homeowners: pick a recurring date in late September or early October, book it once, and let your installer’s diary remind you next year.

When once a year isn’t enough

Twice-yearly servicing genuinely makes sense in a few situations. Worth being honest about which apply to your home.

Heavy usage. If the system runs 8+ hours a day in summer, or you’re using reverse-cycle hard for both heating and cooling across the year (essentially nine months of operation), the wear and tear accumulates faster than an annual service can catch.

Coastal exposure. Homes within a kilometre of the surf cop salt corrosion on the outdoor unit. Sydney’s eastern beaches, Northern Beaches, and parts of the Sutherland shire are the obvious examples. Outdoor units corrode noticeably faster in these locations and benefit from more frequent inspection.

Dusty or high-pollen environments. Western Sydney during summer (Penrith, Liverpool, Campbelltown) carries more airborne dust than coastal suburbs. Properties near construction or with heavy garden coverage load filters faster. Heavy pollen seasons (September through November) accelerate filter loading too.

Pets in the home. Dog and cat hair plus dander load filters and coils significantly faster than pet-free homes. A bi-annual service is worth considering for households with multiple pets.

System age. Older systems wear faster and benefit from closer monitoring. A reasonable cadence: 0 to 5 years annual, 6 to 10 years annual unless other factors apply, 10 to 15 years bi-annual, 15+ years bi-annual minimum and quarterly check-ups worth considering as the system approaches end of life.

Commercial systems are a different conversation

Commercial settings run on different cadences entirely because the operating hours and loads are different. As a rough guide:

Retail and offices: every 3 to 4 months.

Restaurants, gyms, fitness centres: every 2 to 3 months because the cooking loads, humidity loads or occupancy loads are higher.

Medical facilities and data centres: monthly to quarterly depending on criticality. These environments can’t afford unplanned downtime.

24/7 operations: monthly preventive maintenance is standard.

Crown Air handles commercial maintenance contracts separately to residential. The pricing, schedule and scope are all different conversations.

What actually happens during a service

For transparency, because plenty of cheap services advertised online cover roughly half the work below.

A proper residential service includes filter clean or replacement, return air filter check on ducted systems, chemical clean of the indoor evaporator coil, drain pan and drain line flush, refrigerant pressure check against manufacturer spec, leak inspection if pressures are off, electrical safety check on capacitors, contactors and isolators (under AS/NZS 3000), outdoor condenser coil clean, fan motor check, and a full system performance test against rated output.

Refrigerant work specifically requires an ARC-licensed technician under federal law. If a service quote doesn’t mention an ARC licence number, it’s worth asking.

The visit usually takes 60 to 90 minutes for a standard split system, and 90 minutes to 2 hours for a ducted system. Significantly less time than that suggests corners are being cut.

What you can do between professional services

Three things that genuinely matter and don’t require any technical knowledge.

Clean the filters every 4 to 6 weeks during heavy use. This is the single most impactful homeowner job. On a split system, the filter slides out of the front panel of the indoor unit. On a ducted system, the return air filter sits behind a grille on a hallway ceiling or wall. Vacuum, rinse if washable, dry fully, reinstall.

Pour a cup of white vinegar down the condensate drain access every 3 to 4 months. Kills the algae that causes drain blockages, which are one of the most common causes of mid-summer aircon leaks.

Keep the outdoor unit clear. A metre of clearance, no plants growing into it, no leaves accumulating against the fins, no stored items piled around it.

That’s it. Anything past these three is a tech job.

Signs you shouldn’t wait for the next scheduled service

Even with a regular service cadence, certain symptoms warrant getting a tech out immediately rather than waiting.

A musty smell that doesn’t clear within thirty seconds of start-up. Water marks appearing on the wall under a wall split or the ceiling under a ducted indoor unit. Ice forming anywhere on the system. Burning smells. Loud grinding, screeching or banging from the outdoor unit. Frequent breaker trips. A power bill that’s jumped without an obvious explanation. Weak airflow that wasn’t there last season.

These are problems that get worse, not better. The cost of fixing them after they’ve caused secondary damage (a flooded ceiling, a cooked compressor) is dramatically higher than catching them early.

Frequently asked questions

Can I just service my aircon myself? You can clean filters, clear around the outdoor unit, and flush the drain line with vinegar. Anything beyond that (refrigerant, electrical, coil cleaning) needs a licensed technician. Refrigerant work specifically requires an ARC licence under federal law.

What happens if I skip annual servicing? Power bills typically climb 15 to 25%, the chance of mid-summer failure increases significantly, the system’s useful life drops by 3 to 5 years, and most manufacturer warranties become harder to claim against because the warranty terms usually require evidence of regular servicing.

How long does a service take? 60 to 90 minutes for a standard split system. 90 minutes to 2 hours for a residential ducted system. Larger or more complex installs can push to 3 hours.

Is servicing required to maintain my warranty? For most major manufacturers (Daikin, Mitsubishi Electric, Fujitsu, Panasonic), yes. The warranty terms typically require evidence of regular professional servicing. When you make a warranty claim, the manufacturer’s first question is usually “what’s your service history”. No records, no claim. Keep your service reports filed.

Should I service before summer or before winter? For cooling-only use: spring (September-October). For reverse-cycle systems used heavily year-round: spring is the priority service, with an autumn check-up worth considering.

How often should I change my filters? Check monthly during heavy use. Clean or replace every 4 to 6 weeks in summer for most homes. Pets, dust or smoke in the home shortens that interval.

Does servicing genuinely save money? Yes, comfortably. A typical Sydney home running aircon for half the year saves $200 to $500 a year on power bills with a properly maintained system versus a neglected one, on top of the avoided cost of premature failures.

Can servicing improve indoor air quality? Yes. A coil clean and drain flush removes the mould and biofilm that builds up over time, and a clean filter removes more allergens. Households with asthma, hay fever or young children notice the difference.

Will the technician tell me if I need a new system? A good one will. Part of a thorough service is an overall condition assessment, and if the system is past its useful life or facing major repair costs that don’t make economic sense, you should hear that directly. If your installer never mentions condition or age and just bills the service every year, that’s worth asking about.