Assess the causeFollow the evidence.
Assess power supply, remote settings, receiver, protective delays and model-specific controls.
The exact model and operating conditions determine which tests apply. These are possible inspection directions, not a list of components that must be changed.
Before the appointmentKeep the useful details.
Describe indicator lights, displayed codes and whether either indoor or outdoor unit responds.
Record the timing, previous work and accessible model label. Do not remove covers or handle live, refrigerant or pressurised components to obtain information.