Early warning signs your Pakenham system is about to fail.

Every January we take the same call from Pakenham: it worked yesterday and today it is blowing warm air. Almost every time, when we ask the right questions, it turns out the system had been telling the household something for two or three months. A hum on start-up. A vent that stopped keeping up. A smell. A puddle. The failure was not sudden - the diagnosis was just late, and a late diagnosis is what turns a $280 fault into a $2,400 compressor.

Here is the honest list, in the order we most commonly find them on Cardinia jobs.

1. Blowing air, but not getting cold.

Nine times out of ten this is one of three things, and they present identically at the wall. A failing run capacitor, so the compressor tries to start, hums, and drops out on thermal overload while the indoor fan keeps happily blowing room-temperature air at you. A slow refrigerant leak, so the charge has fallen far enough that the coil cannot pull heat out of the air. Or a filthy outdoor coil, so the system cannot dump heat and trips out on high head pressure. A gauge set and a clamp meter separate those three in about fifteen minutes.

What you should not do is keep running it. A compressor starved of refrigerant is a compressor cooking itself, because the refrigerant is also what carries the oil that lubricates it. Two weeks of running undercharged is often the difference between a repair and a replacement.

2. Noises, and what each one means.

• Hum then click, no start: capacitor. $180 to $320. The single most common fault we see and the cheapest to fix if you catch it.
• Buzzing or chattering from the outdoor unit: pitted contactor. $220 to $380. Left alone it welds closed and the compressor never stops.
• Screech or squeal on start: fan motor bearing, or a slipping belt on an older ducted furnace.
• Rattle or vibration: loose panel, a fan blade with debris on it, or a condenser that has walked off its anti-vibration mounts. Cheap. Fix it before it fatigues a line set.
• Gurgling or hissing in the pipework: refrigerant moving through the metering device when it should not be, which usually means low charge.
• Bang or thump on shutdown: a ducted plenum or duct oil-canning as pressure drops. Annoying rather than dangerous, but it points to duct design.

3. Smells - musty is routine, burning is not.

Musty and burning are completely different problems and they get completely different responses. A musty or sour smell on first start each season is biofilm on the indoor evaporator coil. It is very common in the humid Cardinia shoulder months and it is fixed by a chemical coil clean and a condensate drain flush as part of a normal service.

A burning smell is not routine. Switch the system off at the isolator and ring us. Burning usually means an electrical fault - a pitted contactor, a failing fan motor winding, or a scorched terminal, and any repair to that side of the system has to be left in a state that complies with AS/NZS 3000 with a Certificate of Electrical Safety to match. On a ducted gas furnace a hot metallic smell can indicate a heat exchanger problem, and that is a carbon monoxide risk that needs a VBA-licensed gasfitter the same day, not next week. The check that settles it is the spillage and combustion test under AS 4575, the servicing standard for domestic gas appliances, run with a combustion analyser on the flue - that is the only way to separate a scorched-dust smell from a cracked exchanger, and it is not something anyone can judge by nose. Cardinia has a lot of 2002-to-2008 estate homes with original gas ducted furnaces now past twenty years old, and heat exchanger cracking is exactly the failure mode that age brings.

4. Water where water should not be.

A drip from a ceiling vent is urgent. The cause is almost always a blocked condensate drain: the indoor coil pulls litres of water out of the air on a humid Cardinia day, that water is meant to run out through a drain line, and algae and dust block the line. The tray overflows and the water goes into your ceiling insulation and plasterboard. A drain flush is a routine part of a service. Ceiling replacement after a week of quiet overflow is thousands. Turn the system off, put a bucket under it, and ring us the same day.

5. Icing on the outdoor unit in winter.

A light frost on the outdoor coil during a cold Pakenham morning is completely normal on reverse-cycle, and the unit will run a defrost cycle every 40 to 90 minutes to clear it. We get heavy radiation frosts off the Koo Wee Rup flats through July, so Pakenham owners see this more than someone in the inner suburbs does. What is not normal is ice that never clears, ice building on the indoor coil or the copper line set, or a defrost cycle firing every ten minutes. Those point to a failed defrost sensor, a stuck reversing valve, or low charge.

6. The slow ones nobody notices.

These are the signs that never trigger a phone call and cost the most over time. One vent that stopped keeping up - usually a crushed or disconnected flex run in the roof cavity, and on the reactive clay sites across Cardinia we also see plenum connections work loose as the frame moves seasonally. A run time that has crept from twenty minutes an hour to fifty. An electricity bill that has climbed year on year with no change in habits. An unmaintained split loses roughly five per cent efficiency a year as the coils load up, which is $80 to $150 a year straight off your bill and compounding.

2026 costs - what these faults run.

Diagnostic call-out including electrical diagnostic, gauge readings and a written finding: $120-$220. Capacitor $180-$320. Contactor $220-$380. Controller or thermostat $280-$580. Refrigerant leak repair $380-$1,200. Ducted compressor replacement $2,400-$4,800. Full ducted replacement $11,000-$18,000.

Worked example from Cardinia Lakes. Customer rang in November because the split was “a bit slow”. Gauges showed the high side at 1.9 MPa against a 2.8 MPa target - a genuine leak at a flare joint, about eight grams of R32 a month for two years. Leak repair, evacuation and re-charge came to $640. Had they left it until the first 40-degree day the compressor would have run undercharged through the worst of it, and that is a $3,900 job. The whole difference was ringing in November instead of January.

Why is my Pakenham air conditioner blowing air but not getting cold?

Nine times out of ten it is one of three things and they present identically at the wall. A failing run capacitor, so the compressor tries to start, hums and drops out on thermal overload while the indoor fan keeps blowing. A slow refrigerant leak, so the charge has fallen far enough that the coil cannot pull heat out of the air. Or a filthy outdoor coil, so the system cannot dump heat and trips on high head pressure. A gauge set and a clamp meter separate those three in about fifteen minutes. What you should not do is keep running it - a compressor starved of refrigerant is a compressor cooking itself, and that turns a $280 fault into a $2,400 one.

What does a burning or musty smell from my air conditioner mean?

Musty and burning are completely different problems. A musty or sour smell on first start each season is biofilm on the indoor evaporator coil, which is very common in the humid Cardinia shoulder months and is fixed by a chemical coil clean and a condensate drain flush as part of a normal service. A burning smell is not routine. Switch the system off at the isolator and ring us. Burning usually means an electrical fault - a pitted contactor, a failing fan motor winding or a scorched terminal - and on a ducted gas furnace a hot metallic smell can indicate a heat exchanger problem, which is a carbon monoxide risk and needs a licensed gasfitter the same day.

My ducted system is icing up on the outdoor unit - is that normal in a Pakenham winter?

A light frost on the outdoor coil during a cold Pakenham morning is completely normal on reverse-cycle, and the unit will run a defrost cycle every 40 to 90 minutes to clear it. Pakenham gets heavy radiation frosts off the Koo Wee Rup flats through July, so you will see this more than someone in Melbourne's inner suburbs does. What is not normal is ice that never clears, ice building on the indoor coil or on the copper line set, or a defrost cycle that runs every ten minutes. Those point to a failed defrost sensor, a stuck reversing valve, or low refrigerant charge - all real faults that get worse and more expensive if you leave them.

How much does the diagnostic call-out cost and does it come off the repair?

A diagnostic call-out in Pakenham is $120 to $220 in 2026, and it includes the electrical diagnostic, gauge readings and a written finding, not just a look. The repair is quoted separately with a fixed price before we do it, so you decide with a number in front of you. Common outcomes: capacitor replacement $180 to $320, contactor $220 to $380, controller or thermostat $280 to $580, refrigerant leak repair $380 to $1,200, ducted compressor replacement $2,400 to $4,800. If we find the system is genuinely at end of life we will say so rather than sell you a repair that will not pay for itself.

Water is dripping from my ceiling vent - what is it and is it urgent?

Yes it is urgent, and the cause is almost always a blocked condensate drain. The indoor coil pulls litres of water out of the air on a humid Cardinia day, and that water is meant to run out through a drain line. Algae and dust block the line, the tray overflows, and the water goes into your ceiling insulation and plasterboard. A drain flush is a routine part of a service and costs almost nothing. Ceiling replacement after a week of quiet overflow is thousands. Turn the system off, put a bucket under it, and ring us the same day. The second possible cause is a torn or displaced flex duct dumping condensation, which we find by getting into the roof cavity.

Related reading: service and repairs for how we diagnose, the annual service checklist for the twelve checks that catch these early, and emergency aircon repair if it has already stopped. Local detail for Lakeside is on the area page.