Why is my air conditioner running but not cooling?

Start with the controls and airflow

Make sure the controller is in cooling mode rather than fan, dry or heating mode. Set the target a few degrees below the room temperature and allow the system time to respond. If the filter is visibly dirty, clean it using the owner’s manual. Australian Government guidance notes that dirty filters significantly reduce airflow and efficiency.

For a ducted system, confirm the return-air grille is not blocked and that the zones you expect to cool are open. For a split system, check that air is moving freely around both the indoor and outdoor units.

What different symptoms can indicate

• Normal airflow but warm or room-temperature air: confirm cooling mode and allow any manufacturer-described restart delay. If the outdoor unit still does not respond or the outlet air does not cool, the controls, outdoor equipment or refrigerant circuit may need testing.
• Very weak airflow: a blocked filter, fan problem, iced coil or duct restriction is possible.
• Cooling starts and then stops: the unit may be cycling on a control, sensor, airflow or electrical issue.
• Ice on the indoor coil or larger copper pipe: stop the system. Continued operation can add water leakage and does not identify the underlying cause.
• Only one room is affected on a ducted system: zoning, duct or outlet issues may be more likely than a complete system failure.

For ducted air conditioning, use the whole-system versus one-zone guide to record which rooms, zones and equipment still respond.

Is this servicing or fault diagnosis?

A gradual airflow decline with an overdue, dirty system and no discrete fault may fit planned servicing and cleaning. Sudden warm air, a stopped fan or outdoor unit, ice, water, an error code, unusual noise or breaker operation requires diagnosis rather than booking a routine clean and hoping it resolves the fault.

When a technician is needed

Book a diagnosis when correct settings and a clean filter do not restore cooling. A technician can compare temperatures and airflow, inspect fans and coils, read fault history where supported, test electrical components and assess the refrigerant circuit. Refrigerant should not simply be “topped up” without finding why charge may be low.

Neighbourhood Electrical & Air provides air-conditioning repairs across Perth for split and ducted systems.