Air Conditioner Not Cooling? What Is Usually Going Wrong in Cairns Homes

The call usually goes the same way. The air conditioner is on, the fan is running, the remote says 22, and the room is sitting at 28 and not moving. It is the most common fault we look at across Cairns once the first warm weeks of September arrive, and most of the time it comes down to one of a small number of causes.

Some of those you can check yourself in ten minutes. Some of them need a licensed technician, and the difference matters, because the ones that need a tech get worse and more expensive the longer the unit keeps running.

Start with the two things you can check yourself

• The filters. Lift the front panel on the indoor unit and slide the filters out. If they are grey and matted, the unit cannot pull enough air across the coil to cool it, so it runs flat out and achieves very little. Wash them, dry them completely, put them back. In the tropics this is a monthly job, not a yearly one.
• The outdoor unit. Go outside and look at the condenser. If it is boxed in by plants, packed with leaves, or has a fence or a bin sitting hard against it, it cannot dump heat and the whole system loses capacity. Clear a good gap around it. On the beaches, from Machans Beach up to Palm Cove, a gentle hose with fresh water gets salt off the fins.

If both of those are clean and clear and the room still will not come down, the problem is inside the system and it is time to stop running it.

The causes a technician actually finds

A coil that needs a proper clean. Filters catch the coarse stuff. The fine dust, and the mould that grows on a permanently wet coil in Cairns humidity, sits on the coil itself. A coated coil cannot exchange heat properly, and the unit runs for hours to do what it used to do in twenty minutes. This is the single most common thing we find, and it is fixed with a chemical clean, not a part.

Low refrigerant. A split system is a sealed circuit. If the refrigerant is low, it has leaked, and topping it up without finding the leak just means paying for the same gas again in a few months. A tech will pressure test the system, find the leak, repair it, then recharge to the manufacturer weight. Ice on the pipework or on the face of the indoor coil is the classic sign.

A failed capacitor or fan motor. If the outdoor unit hums but the fan is not spinning, or it starts and stops within a minute, the start capacitor or the fan motor has usually gone. Both are straightforward repairs when caught early. Left alone they take the compressor with them, and a compressor is the expensive part of the whole machine.

A blocked drain. Most modern units have a float switch that shuts the cooling down when the condensate tray fills. In the build-up a drain line blocks with slime very easily, the tray fills, the unit quietly stops cooling and just runs the fan. Water marks on the wall under the indoor unit usually go with it.

Simply undersized. Sometimes nothing is broken. A unit chosen for a bedroom that is now cooling an open-plan living area with west-facing glass will run all afternoon and never get there. That is a sizing conversation, not a repair.

Why it is worth stopping the unit rather than pushing on

An air conditioner that cannot reject heat runs at higher pressures and higher temperatures than it was designed for. A dirty coil overloads the compressor. Low gas can starve it of the oil it needs. A stuck fan cooks it. The repair that costs a service call this week can turn into a replacement by Christmas if the unit is left to grind through a Cairns summer in that state.

Refrigerant is licensed work

Anything that opens the refrigerant circuit is licensed work in Australia. FNQ Air Solutions Pty Ltd holds ARCTick refrigerant handling licence AU62644 and QBCC licence 15533799, both checkable on the public registers. Filters and clearing the outdoor unit are yours to do. Gas, electrics and anything inside the cabinet are ours.

Getting it looked at

We do fault finding and repairs across Cairns and the inner suburbs, Stratford, Freshwater, Redlynch and Brinsmead, the beaches from Machans Beach through Trinity Beach to Palm Cove, south through Edmonton and Gordonvale, and up the Range to Mareeba and Atherton. If the unit is not broken but has just never been serviced, the pre-summer maintenance offer is running through September and October. Tell us the suburb and what the unit is doing and we will tell you which one it needs.