A unit that runs but no longer cools is the single most common call we receive. In most cases the cause is one of five faults, and the first two can be checked in a few minutes without any tools. Work through them in order before booking a call-out.
1. Start with the simple checks
Confirm that the indoor unit is actually in cooling mode and not on fan, dry or heat. The set point must sit at least five degrees Celsius below the room temperature, otherwise the compressor will simply idle. Check that the outdoor isolator is switched on and that the circuit breaker has not tripped. If the display is dead, the problem is electrical rather than refrigeration.
2. The five faults we find most often
- Blocked filters. Dust restricts airflow across the coil, so the unit moves air but delivers no real cooling. Wash the filters under running water every month during summer and let them dry fully before refitting.
- A dirty outdoor condenser. If the outside coil is caked with dust, lint or leaves, it cannot reject heat. The compressor then runs hot and either trips on its safety or cools poorly.
- Low refrigerant charge. A slow gas leak is the classic cause of a unit that cooled well last summer and barely cools now. Topping up gas without finding and repairing the leak only postpones the same failure.
- A failed capacitor or compressor. A weak start capacitor stops the compressor from starting, so the fan blows air that is the same temperature as the room. This needs meter testing on site.
- A frozen indoor coil. Ice on the evaporator usually points to restricted airflow or low charge. Switch the unit off and let the ice melt completely before running it again.
3. Error codes are useful evidence
Most modern inverter units flash a code when a sensor, communication line or pressure switch misbehaves. Photograph the code before you reset the unit, because a reset clears the history and the technician loses the fastest route to the fault.
4. When to stop and call a technician
Stop troubleshooting and book a qualified technician when you see ice forming on the pipework, smell burning, hear repeated clicking from the compressor, or notice oil residue around the pipe connections. Refrigerant work is regulated, so gas handling, pressure testing and electrical diagnosis belong with a registered technician.
Legacy Air attends breakdowns in Mulbarton and across greater Johannesburg, generally within 24 to 48 hours, and prioritises no-cooling faults. A diagnostic visit identifies the true cause before any repair is quoted, which means you approve the cost with the fault already confirmed.