Which AC noises are normal and which are not?
A steady low hum, the whir of the condenser fan, and a click when the system starts or stops are normal. Grinding, squealing, metal on metal, loud knocking, or a sound that is new and harsh are not, and they deserve attention before the system is run much longer.
Every system has its own sound. What matters is a change. If your outdoor unit has always hummed and now rattles, something has shifted, whether it is a loose panel, a failing fan motor or the compressor.
Noise from the indoor air handler is a separate topic. Squeals there often involve the blower motor or belt, and a rattle can be a loose panel or duct.
What does a hum and click from the outdoor unit mean?
A hum and click from the outdoor unit usually means the compressor is getting power but is not starting. Common causes are a failed start or run capacitor, a worn contactor, or a mechanically stuck compressor. The system may then shut off on its overload protection and try again.
Capacitors are common failures in Arizona heat, and replacing one is a routine repair for a technician. Repeatedly forcing a unit to try to start can make things worse, especially if the cause is a seized compressor.
Capacitors store a charge even when power is off, so do not open the electrical compartment. Turn the system off at the thermostat and the breaker, and let a licensed technician test it.
Can you keep running an AC with a noisy compressor?
You should not keep running an AC with a loud, harsh compressor noise. Grinding or metal on metal can mean internal damage, and continued running may turn a repair into a full replacement. Turn the system off at the thermostat and the breaker, then call for service.
That said, a house in a July heat wave makes waiting hard. Use fans, close blinds, and move to the coolest room while you arrange service. Elderly residents, young children and pets should not stay in a hot home.
Vortech is open 24 hours per our Google profile and has licensed AC technicians, so an emergency call during a monsoon night is something we can discuss by phone.
Is a bad compressor worth repairing?
Whether a bad compressor is worth repairing depends on the age of the system, the type of refrigerant, the condition of the rest of the equipment and the cost of the part and labor. A technician can compare repair and replacement once they see the unit and run tests.
Older systems that use R-22 are especially hard to justify repairing, because production of that refrigerant ended in 2020. Newer residential systems use newer refrigerants such as R-454B or R-32, and parts and procedures differ.
Asking for a written explanation of what failed, and whether the cause was a capacitor, a refrigerant leak, a dirty coil or an electrical issue, helps you decide. A failed compressor is sometimes a symptom of another problem.
More questions: AC Repair: 12 Most Asked Questions Answered