By Steve, co-founder AC Store | Published: 15 September 2026 | Last updated: September 2026
It’s early September 2026. The mornings are still cool, the afternoons are creeping up, and this week the first person in the house switched the aircon on for the first time since April and said the words no South East Queensland homeowner wants to hear three months out from summer: “I don’t think it’s cooling properly.”
We’ve been called out to 10,000+ SEQ homes across Brisbane, Moreton Bay, the Sunshine Coast and Hervey Bay. Nine times out of ten a system that’s running but not cooling has one of five causes: (1) clogged filter, (2) dirty or damaged outdoor condenser, (3) blocked condensate drain, (4) low or leaking refrigerant, or (5) undersized or past its serviceable life. Three you can check yourself in ten minutes; two need a licensed technician.
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First, is it actually not cooling, or is it under-set for the room?
Before we blame the equipment, run the sanity check. Confirm cool mode (snowflake), not FAN, AUTO or HEAT. A Daikin “cool mode not working” call almost always lands here after the controller was left in AUTO over winter. Set the target to 22–24°C, not 18°C; a system asked to hit 18°C on a humid Brisbane afternoon runs flat out and still can’t get there.
Change the remote batteries, check the room sensor isn’t in direct sun, and confirm vents aren’t closed and the west-facing door isn’t letting the 3 p.m. sun straight in. A 2.5 kW split cooling 32 m² of west-facing glass in Aspley will always struggle.
Quick kW-to-m² guide for SEQ homes
Across BCA Climate Zone 2 (coastal SEQ), we size around 0.15 kW per m² for well-insulated interiors, stepping up for west-facing, poorly-insulated or Queenslander rooms:
| Room size | Standard well-insulated | West-facing / Queenslander / poor insulation |
|---|---|---|
| Up to 20 m² (bedroom) | 2.0–2.5 kW | 2.5–3.5 kW |
| 20–35 m² (living) | 3.5–5.0 kW | 5.0–7.1 kW |
| 35–60 m² (open-plan) | 6.0–8.0 kW | 8.5–10.0 kW |
| Whole 4-bed lowset (Griffin / Mango Hill) | 10–13 kW ducted | 13–16 kW ducted, zoned |
If your kW is well below the right band, no amount of troubleshooting will fix it.
The 5 self-checks you can do this weekend
These are the checks our service team runs first on every call-out. Three of them you can do yourself with a screwdriver and a garden hose.
1. Clean or replace the filters
Pull the front panel off your indoor unit (most flip up on two clips), lift out the mesh filter and hold it to the light. If you can’t see through it, wash it under warm water with a soft brush, dry in the shade, and reinstall. Clean every 4–8 weeks in summer. A clogged filter is the single most common cause of a system that “just isn’t cooling like it used to”: airflow drops, the coil ices over, and cooling collapses.
2. Check the outdoor condenser, leaves, debris, salt corrosion
Switch off at the isolator, then walk to the outdoor unit. Clear leaves and spider webs from the fins and fan grille. Gently hose the fins from the inside out (never a pressure washer). On coastal Sunshine Coast and Hervey Bay homes we constantly see condensers that have lost 30–40% of their heat-exchange area to salt corrosion within 5–7 years. White, chalky or eaten-away fins mean a professional coil clean or a coastal-grade replacement.
3. Check for ice on the indoor coil
Look at the copper coil behind the filter and the insulated pipe to the outdoor unit. If you see frost or ice, switch off for 2–3 hours to thaw fully (put a towel down; it drips), run FAN mode for 30 minutes to dry, then try COOL again. If it re-ices within a day: low refrigerant, fan fault, or still-restricted filter. Book a technician.
4. Check the condensate drain
The sleeper August–October call across SEQ. Over a wet summer, condensate drains fill with algae, then dry over winter into a solid plug. When you switch on in late August, the pan fills, the safety float trips, and the system won’t cool. Water pooling under the indoor unit, or the outdoor drain hose not dripping when it’s running hard, means the drain needs flushing.
5. Check the isolator and any tripped RCD after storm season
Ex-tropical cyclone Alfred hit SEQ in early 2025 and a chunk of the fan-motor and capacitor failures this spring trace back to those storm-season surges. Look at the switchboard for a tripped RCD or breaker. Reset once. If it trips again, stop: that’s an electrical fault.
What each fault looks like on your specific system
Most guides lump every aircon type together. They shouldn’t: faults look different on each.
Split system running but not cooling
Fan runs, air comes out, but it’s room-temperature. Usually one of three things: the outdoor unit isn’t running (isolator tripped, capacitor failed after a storm surge), refrigerant is low from a slow flare-joint leak, or the filter is choking airflow. Walk outside: if the outdoor fan is still, call a technician. If it’s spinning and the pipe insulation isn’t cold after 10 minutes, refrigerant is low. Compare a replacement split if the unit is 10+ years old.
Ducted system cooling one room but not another
Almost never a refrigerant issue, and almost always zoning, airflow or duct. With AirTouch, MyAir or Zonemaster, one damper stuck closed will starve a zone. One blocked return-air filter kills static pressure to the whole house. In older ducted installs across Bridgeman Downs, Carseldine and Warner we regularly find torn flexi-duct dumping cool air into roof insulation. Book a ducted inspection.
Portable and window/wall units
Portables are always the weakest option; single-hose units vent as much conditioned air back outside as they blow in. Cooling a 25 m² living room with a portable in a Brisbane summer isn’t a fault; it’s the physical limit of the design. Window and wall units are usually undersized, dust-blocked or drawing air from the wrong side; clean the filter, clear the outdoor side, and confirm the room is under 20 m². Older units running R22 are on borrowed time.
Evaporative cooler not cooling on humid days
Evap coolers add moisture to the air, which works in dry heat but not Brisbane humidity. On a 30°C day at 75% humidity, an evap unit blows warm damp air. There’s no fix. If you’re relying on evap in SEQ, it’s time to look at reverse-cycle.
Brand-specific quirks and error codes to look out for
We install and service every major brand sold in Australia. Each has its own tells.
Daikin. “Cool mode not working” is almost always the controller stuck in AUTO. Wall-controller error codes. U0 (low refrigerant), U4 (indoor–outdoor comms), A5 (freeze protection).
Mitsubishi Electric. MSZ error codes flash on the indoor unit’s operation light, count the blinks. The most common not-cooling call is a blocked drain triggering P8.
Fujitsu. Lifestyle Range is a workhorse but outdoor units are salt-sensitive. Within 5 km of the beach, book an annual coastal service.
LG. Efficient dual inverter, but the ThinQ app can lose Wi-Fi config after a power outage, factory-reset the controller before assuming a fault. LG’s 10-year warranty is compressor-specific.
Panasonic. CS/CU series; error codes come out on the remote when you hold timer/check.
Samsung. Digital Inverter runs fan-only if the outdoor unit can’t communicate, check the isolator and comms cable at the outdoor terminal.
Midea, Hisense, Haier, Gree, TCL, Kelvinator, Carrier, Hitachi. The most common issue is refrigerant loss at a factory-crimped flare within 3–5 years, needs an ARCtick tech.
Bonaire / Cool Breeze (evap). Almost always a blocked water pad or stuck pump. A working evap still won’t cool a humid SEQ afternoon.
When it’s time to stop DIY and call a licensed technician
Red-line signs. Stop and book a call:
- Refrigerant: ice that comes back after thawing, hissing near flare joints, oily residue on pipework, or air noticeably warmer than it used to be.
- Compressor: outdoor unit won’t start, hums for a few seconds then trips, or a loud clunk on startup.
- Electrical: burning smell, a breaker that trips more than once, or a controller that lights up but never runs the unit.
Two firm lines. Refrigerant handling (including regas) must be done by an ARCtick-licensed tech. Fixed-wired electrical work must be done by a licensed electrical worker under the Electrical Safety Act 2002 (Qld). Our in-house team holds both. We don’t sub out.
Cowboy-installer red flags. Walk away if you see any of these:
- Quotes a regas without giving you an ARCtick number.
- Cash-only, no ABN, no written quote.
- Offers to do the fixed-wired electrical work themselves without a QLD electrical worker’s licence.
- Recommends a bigger kW because “bigger cools faster”. It doesn’t; it short-cycles and destroys humidity control in a SEQ summer.
Repair or replace? An honest decision framework
Here’s the framework we walk every SEQ homeowner through. It’s the same one we use with our own families.
Age. Under 8 years, usually worth repairing. Over 10 years and needing a compressor or refrigerant repair, replace.
Refrigerant type. If the outdoor sticker says R410A (or worse, R22) and it needs a regas, you’re pouring money into a phase-out gas. HFC quota cuts have pushed R410A regas prices up sharply. R32 replacements are cheaper to run and service.
Repair vs new install. Once the repair exceeds 40% of a like-for-like replacement, replace.
Efficiency delta. A 2026 R32 inverter split runs 30–40% cheaper on power than a 10-year-old fixed-speed unit: often $300–$600 per year on a whole-home ducted setup.
2026 AUD indicative install pricing bands (SEQ):
- Single-head split supplied & installed: $2,500–$4,500
- Multi-head 3-zone split: $6,500–$11,000
- Ducted 4–6 zone: $10,000–$18,000
- Premium ducted with AirTouch zoning: $15,000–$25,000
Pricing is indicative, request a free measure-and-quote for a fixed number on your home.
Interest-free worked example. A $12,000 ducted replacement on our 6–60 month interest-free finance works out around $200/month over 60 months at 0% interest, subject to approval and finance-page terms.
Why we’re telling you this in August, not December
Our lead time in early September is around a week. By early December it’s four-plus weeks, and every installer in Brisbane and on the Sunshine Coast is booked through Christmas. Two in three of the “urgent, no cooling” calls we take in December to February were preventable: the fault was already there in August, and the homeowner just didn’t test the system until the 34°C day.
Cheaper now, faster now, and you’re not doing it in a 34°C ceiling cavity. Book a pre-summer service this month and, if replacement is the smarter call, you’ll have the new system commissioned before the first heatwave.
Frequently Asked Questions
Why is my aircon running but not blowing cold air?
Across 10,000+ SEQ installs, the most common causes are a clogged filter, a dirty outdoor condenser, or low refrigerant from a small leak. The first two you can check yourself; low refrigerant needs an ARCtick tech, and you should never top up without finding the leak.
Can I regas my aircon myself?
No. It’s illegal in Australia without an ARCtick licence. R32 and R410A are regulated under the Ozone Protection and Synthetic Greenhouse Gas Management Act 1989. Any Queensland technician offering a regas should be able to show you their ARCtick number.
My split system fan works but it’s blowing warm air, what’s wrong?
Usually one of three things: stuck in FAN or HEAT rather than COOL, the outdoor unit isn’t running (isolator tripped, capacitor failed after a storm surge), or refrigerant is low from a leak. Check the mode and the outdoor unit first.
How long should a split system last in Brisbane and on the Sunshine Coast?
A quality inverter split typically lasts 10–15 years in SEQ, with coastal Sunshine Coast and Hervey Bay units at the shorter end because of salt corrosion. If your unit is 10+ years old, R410A, and needs a compressor or major refrigerant repair, replacement usually beats repair on a 3–5 year payback.
Why does my aircon cool better on some days than others?
SEQ humidity. On humid days the system has to condense moisture out of the air, which uses a lot of its capacity. An undersized or dirty system will feel like it’s “not cooling” on a 30°C humid day when it was fine at 26°C dry.
Do I need to service my aircon before summer?
Yes. Every 12–24 months, ideally in late winter or early spring, so issues surface before the December heat. A service covers filter, coil, condensate drain, refrigerant pressure and electrical safety.
Is it worth repairing an old aircon or replacing it?
Rough rule: if the unit is 8+ years old and the repair is over 40% of a new install, replace. R410A units are increasingly expensive to regas. A 2026 R32 inverter runs 30–40% cheaper on power than a 10-year-old fixed-speed unit.
I’m a landlord, do I have to fix my rental’s aircon under Queensland law?
Under the Queensland Minimum Housing Standards (in effect for all tenancies from 1 September 2024), a rental must be reasonably safe and functional. Cooling in the main living area is increasingly treated as a habitability issue in SEQ, so a non-functional aircon that’s part of the advertised inclusions should be repaired or replaced promptly. Verify current guidance with the RTA.
Get the SEQ team on it, or shop the replacement
If you’ve worked through the checks and it’s still not cooling, don’t let it sit until January. Book a service call with our licensed team. Brisbane, North Lakes, Mango Hill, Aspley, Carseldine, Warner, Caboolture, Burpengary, Deception Bay, Redcliffe, Narangba, Kawana, Buderim, Caloundra, Maroochydore, Nambour, Coolum, Palmview, Gympie, Hervey Bay and Carindale.
If it’s time to replace, request a free split system quote or ducted quote, or come see a modern R32 inverter running at our North Lakes, Kawana or Deception Bay showroom.
About the author
Steve is co-founder of AC Store and has spent 15+ years designing, installing and servicing air conditioning across Brisbane, Moreton Bay, and the Sunshine Coast. AC Store: LG National Dealer of the Year 2024–2025, 10,000+ SEQ installs, three locations (North Lakes, Kawana, Deception Bay warehouse). More about the team.
Published: early September 2026 | Last updated: 25 August 2026 | Next scheduled refresh: March 2027