What does a locked compressor look and sound like?
A locked compressor typically hums loudly, may click, and then the breaker trips or the unit shuts off without ever running. The outdoor fan may spin normally while the compressor stays silent or struggles. Turn the system off and leave it off until it is checked.
Many people hear a hum and assume the compressor is seized. That hum is also what a failed start capacitor sounds like.
Do not keep turning the system on to see if it catches. Each failed attempt pulls heavy current and can overheat windings and wiring.
Does the old trick of tapping the compressor work?
Tapping or hitting a compressor is not a safe repair. It can damage the housing, refrigerant lines and wiring, and if it ever seems to work, the underlying wear is still there and the failure will return. Leave the diagnosis to a licensed technician.
Sometimes a part starts after a bump because a stuck contactor or loose connection shifted. That is luck, not a fix.
The compressor is a sealed part full of pressurized refrigerant and electrical connections. Forcing it is a good way to turn a small repair into a large one.
What does a technician check before condemning it?
A technician tests the electrical supply, capacitor and contactor, then measures the compressor windings and amp draw. These checks separate a truly seized compressor from a cheaper electrical part that is keeping a healthy compressor from starting. Those electrical parts are far cheaper to replace.
They may also check refrigerant pressures and look for signs of overheating or oil contamination. Findings guide the repair choice.
Ask the technician to explain which test showed what. A clear answer should tell you whether the compressor or something smaller failed.
What causes a compressor to seize?
Seizing usually follows long-term stress: overheating from dirty coils, low refrigerant, lack of lubrication, repeated hard starts, electrical surges, or simple age. Desert heat and long run times make these causes more common in Arizona. Often more than one cause is at work.
Monsoon surges and power flickers can stress a compressor motor. Whole-house surge protection is one way to reduce the risk.
Regular maintenance catches dirty coils and weak capacitors before they push the compressor past its limit.
What are my options if the compressor is truly seized?
The options are replacing the compressor or replacing the outdoor unit or the whole system. The right choice depends on system age, refrigerant type, condition of the coil and air handler, and how the repair compares with new equipment. A technician can walk you through the tradeoffs.
Older systems that use R-22 often tilt toward replacement, since that refrigerant stopped being produced in 2020. A technician can explain what your equipment uses.
Turn the unit off until it is checked. Vortech Air-Conditioning & Electrical is licensed for AC and electrical work, so wiring and breaker questions can be handled in the same visit. Use the call button on this page.
More questions: AC Repair: 12 Most Asked Questions Answered