The most common signs of air conditioning problems can be broken down into four categories:
Noises - Changes in the sounds your air conditioner makes usually mean a problem.
Reduction in cooling - A system that is blowing hot air from the vents indicates the need for a service call.
Reduced airflow - A decrease in airflow can be due to a blockage, a vent issue or a problem with a fan or fan motor.
Escalating electricity bills - Unexpected spikes in monthly cooling costs can be due to a malfunctioning system.