10 Signs Your Air Conditioner Needs Repair

1. Weak airflow — often a blocked filter or failing fan motor. Filters should be washed every 6–8 weeks in a house with pets; every 12 weeks otherwise.

2. Warm air coming out on cool mode — likely refrigerant leak. Refrigerant doesn't 'wear out' — if the charge is low, there's a leak somewhere in the pipework or coils.

3. Musty smell — mould on the blower wheel or drain pan. This is by far the most common indoor-air-quality complaint we deal with.

4. Water leaking indoors — blocked condensate drain. Ignore this and you'll be repairing ceiling plaster too.

5. Ice on the outdoor unit — refrigerant charge issue, airflow restriction, or a stuck reversing valve.

6. Clicking or rattling — failing fan bearings, a loose component, or a compressor that's about to give up.

7. Tripping the circuit — compressor issue, short, or a failing capacitor. Never keep resetting the breaker — you can cause an electrical fire.

8. Short-cycling (turning on and off repeatedly) — thermostat, oversized unit, or refrigerant charge issue.

9. Rising electricity bills — inefficiency from dirty coils, a failing part, or a stuck defrost cycle running when it shouldn't.

10. Unit over 10 years old with a big repair — consider replacement.

A blocked filter caught early is a $0 fix (wash it yourself). Left for six months it becomes a $180 service call. Left for two years it becomes a $2,400 compressor.

A refrigerant leak caught early can be brazed and recharged for $400–$700. Ignored, the compressor eventually runs dry and seizes — $2,000–$3,500 to replace, or the unit is written off.

The pattern is consistent: small problems compound quickly in air conditioners because everything runs off the compressor, and the compressor is the single most expensive component.

Filter — pop it out, hose it off, let it dry, put it back. Under 5 minutes.

Outdoor unit — is the fan spinning when the system is calling? Is there debris blocking airflow (leaves, cobwebs, grass clippings)? Clear it away with the power off.

Drain line — is water pooling under the outdoor unit or the indoor unit? A gentle vacuum on the drain line outlet clears many blockages.

Remote settings — cool vs heat vs fan-only vs dry. Sounds trivial but a surprising number of 'not cooling' calls are a remote in dry mode.

Anything involving the refrigerant circuit — that's ARCtick-licensed work by law.

The electrical panel or capacitors — mains voltage, and capacitors store dangerous charge even after power-off.

The compressor or reversing valve — specialist parts and diagnostic gear needed.

A useful rule of thumb: if the unit is over 10 years old and the repair is more than 40% of a new install, replace.

Also replace when: the compressor is failing on an R22 unit (the refrigerant is phased out and pricey), when there's a second major fault in the same year, or when a new unit would be at least two star ratings better (payback in energy savings is often 5–7 years on a well-used system).

Annual service in autumn or spring. Filter cleans every 6–8 weeks. Keep the outdoor unit clear of vegetation on all four sides. Run fan-only for 10 minutes after a heavy cooling session. Don't cycle the setpoint by more than a couple of degrees an hour.

Homes that do those five things routinely see roughly half the repair rate of homes that don't. It's the closest thing to a free extension of unit life we know.

Most AC failures happen at the change of season, not during peak use. The first cold morning in April and the first hot day in November are our two busiest weeks of the year.

The reason: parts under stress deteriorate through the shoulder season without you noticing. When the system is finally asked to work hard, the marginal part fails.

A pre-season service catches most of these before they turn into an emergency callout at Christmas Eve rates.

Refrigerant gauges (weight-in scale, digital manifold) to confirm charge.

Clamp meter to measure current draw against manufacturer spec — reveals a struggling compressor before it fails.

Infrared thermometer on supply and return air — a healthy split delivers a 10–14°C differential on cool mode.

Manometer for static pressure on ducted systems — reveals blocked filters, kinked flex, or oversized dampers.

Manufacturer warranties on major brands are typically 5 years parts, 5 years labour. That covers most inherent defects.

Home contents insurance rarely covers AC repair unless it's storm damage or a specific electrical fault. Read your PDS.

Installer workmanship warranty (2–5 years) covers pipework, mounting, and commissioning errors. Keep the paperwork.

Emergency: no cooling on a 38°C day, no heating on a −3°C night, water leaking through a ceiling, burning smell, tripping breakers.

Standard: musty smell, remote not working, one zone not reaching setpoint, mild efficiency drop.

Emergency callout fees typically add $150–$300 to the base diagnostic. If it can wait 24 hours, book standard.

Manifold gauges, weight-in scale, vacuum pump, leak detector, digital multimeter, clamp meter, infrared thermometer, manometer, spare capacitors in common sizes, a laptop with manufacturer diagnostic software, and a full electrical test lead set.

Most no-cool and no-heat calls are solved on the first visit with parts from that kit. When they aren't, it's usually a compressor, board or coil that needs to be ordered.

'Your unit needs a full gas regas' every visit — refrigerant doesn't wear out. If it's low, there's a leak that needs finding.

'The compressor is failing' with no measured evidence — should be backed by current draw readings.

'You need a whole new system' for a unit under 8 years old with a modest fault — get a second opinion before writing off a $5,000+ system.

Once past 10 years, focus on cheap wins: annual service, filter discipline, coil cleans, and avoiding heavy setpoint swings. These can add 2–4 useful years to a marginal unit.

Don't spend big on a unit past 12 years old. A $2,000 compressor rebuild on a 14-year-old unit is throwing good money after bad.

1. Faint hissing near the outdoor unit — small refrigerant leak.

2. Bubbling or gurgling at the drain outlet — partial blockage.

3. Vibration transmitted through walls — mounting brackets loosening.

4. Longer run times to reach the same setpoint — efficiency drift, usually coil fouling or a small refrigerant loss.

5. Uneven temperatures room-to-room on a ducted system — zone damper actuator wearing out.

6. Remote controller lagging or missing commands — flat batteries, IR sensor drift, or Wi-Fi module failing.

7. Occasional cold gust in heat mode — normal defrost, but if it lasts >6 minutes or happens every 20 minutes, the defrost sensor may be sticking.

8. Slight burnt smell only on startup — dust burning off after long idle. Normal on first winter startup, worth checking if it persists.

9. Whistling from vents — restricted airflow, usually a very dirty filter or a partially-closed damper.

10. Compressor 'hunting' — cycling on and off every few minutes even at moderate load. Points to sensor calibration or refrigerant charge.

Blocked filter or fouled coil: roughly 30% of no-cool and no-heat calls. Cheap to fix, expensive if ignored.

Refrigerant leak: roughly 20%. Needs an ARCtick technician to find and braze.

Failing capacitor: roughly 15%. $150–$280 to replace, and prevents the compressor damage that would otherwise follow.

Together those three account for two thirds of the diagnostic calls we run in Canberra. The remaining third is a long tail of boards, sensors, valves, contactors, motors and drainage.

Written invoice with model number, serial number, date, technician name and ARCtick number.

Parts fitted with part numbers.

Refrigerant weight added or recovered.

Test measurements after repair (pressures, current draw, supply air temp).

Warranty terms on the specific repair (usually 12 months parts and labour).

Keep every invoice in a folder with your original install paperwork. It matters when you sell the house.

Say what mode you were in (cool, heat, dry, fan). Say what the setpoint was and what the room felt like.

Note the outdoor unit — is the fan turning? Any unusual noise? Any ice visible?

Note the indoor unit — any error codes flashing? Any smells? Any leaks?

Note when the fault started and whether it's constant or intermittent.

Send a short phone video if there's a noise or a flashing code — it saves 15 minutes on the visit and often narrows the fault before we arrive.

Capacitors on the outdoor fan and compressor at year 8–10 — cheap ($150–$280), prevents a compressor damage cascade.

Contactors showing pitted contacts at year 10 — $180–$260 to replace, prevents intermittent no-start faults.

Drain pans on units with visible corrosion at year 10+ — $220–$400 to replace, prevents ceiling water damage.

Not everyone opts in to prophylactic replacement. It's cheaper on the day, but avoids emergency callouts later.