This is not an easy question to answer and may be caused by a long list of possible questions. If your AC is not working properly, you can narrow down the list of possibilities by answering a few short questions.
If you are satisfied with the power and there is a correctly marked circuit breaker panel outside, you can check the circuit breaker for tripping. This is an outdoor circuit breaker panel that provides 230V power for outdoor AC units and other appliances, as opposed to the 110V / 120V power for living Spaces typically found in garages or laundry rooms. If the circuit breaker trips, reset it and check to see if the device is powered back on. Please note that most newer systems and thermostats have a 5-7 minute time delay from when the device is turned on to when the system is running, so please be patient.
If the equipment is not restarted or the circuit breaker immediately trips again, the problem is most likely a defective compressor (short-circuited to the ground), which requires a professional to diagnose the problem and cite AC repair and alternatives.
If the device does restart and continues running, it is likely that the device has triggered an overload or pressure switch. The system may continue to operate (possibly indefinitely), but we still recommend that you have the system checked by a qualified technician as early as possible to prevent a recurrence of a failure that could be caused by a root cause - or a possible major component failure.
If the outdoor unit is not running but the indoor unit is blowing air, this may be due to dirty or blocked air filters or coils, blocked condensate outlets, insufficient refrigerant, or a failure of one of several components in the outdoor unit.
This is usually caused by defective blower motors or blower motor capacitors. Qualified technicians can identify problems and may store parts on their trucks so necessary repairs can be made at the time of diagnosis.
Neither the indoor unit nor the outdoor unit works? If neither unit is running, the list of possible problems becomes long. The general temperature controller will not be displayed, indicating that the system does not have electricity. This could be as simple as tripping a float switch (water safety switch) caused by a blocked drain.
If necessary, reset the circuit breaker and determine whether the system is restarted. As a reminder, once power is restored, there may be a 5-7 minute delay before the system restarts. However, the thermostat should display should be restored immediately. If the system is not restarted, we recommend that you call a qualified technician to check and diagnose the reason why your air conditioner is not working. If it is restarted and running properly, everything is fine, and the problem could be caused by some kind of power failure from an external source. However, if problems recur, we recommend diagnosis by a professional HVAC contractor.