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HomeRepair HelpCarrier Central A/C RepairCarrier Central air conditioner compressor won't run Repair
Carrier Central air conditioner compressor won't run
When a Carrier central air conditioner compressor won't run, the compressor may be defective or worn out, but that is not usually the most common cause. The start capacitor is the next likely problem because a failed capacitor can prevent the compressor from starting, especially if it is bulging, leaking, or cannot hold a charge. A defective contactor can also stop the compressor by preventing voltage from reaching the outdoor condensing unit. Less common causes include a failed run capacitor, capacitor, or dual run capacitor, which supplies starting or operating power to the compressor and condenser fan motor. These issues can cause an air conditioner compressor not to start, a central AC compressor not working, or an AC compressor humming but not starting. Testing compressor continuity and capacitor performance requires a multimeter and electrical safety knowledge. The contactor, capacitors, and compressor involve hazardous 240-volt electricity, so have a qualified HVAC technician handle line-voltage testing or replacement. Any repair inside the sealed refrigerant system requires an EPA 608-certified technician. Enter your Carrier model number to find the exact replacement part for your specific central air conditioner.
01 - Carrier Central Air Conditioner Compressor
The compressor is a pump which compresses the refrigerant and circulates the refrigerant through the evaporator and condenser coils. If the compressor is defective or worn out, it likely won't run. However, this isn’t usually the case. Before replacing the compressor, first check all of the more commonly defective components. If all of the other components are working properly, use a multimeter to test the compressor for continuity. If there is an open circuit, the compressor is likely defective.
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Highly Likely
02 - Carrier Central Air Conditioner Start Capacitor
A start capacitor is often used to cycle on the compressor. If the capacitor burns out, the compressor may not run. The start capacitor can be tested with a multimeter to determine if the component can successfully hold and release its charge. If the capacitor is unable to hold and release a charge, or is bulging or leaking, the capacitor will need to be replaced.
Common
03 - Carrier Central Air Conditioner Contactor
The furnace control board sends a low voltage signal to the contactor. When the contactor receives the signal from the control board, it closes the circuit, sending voltage to the condensing unit components. If the contactor is defective, it can prevent the compressor from running. To determine if the contactor is at fault, use a multimeter to test the contactor coil for continuity. If the contactor coil does not have continuity or the contacts a on the coil look burnt, replace it.
Common
04 - Carrier Central Air Conditioner Run Capacitor
A run capacitor will power either the compressor or the fan motor (a dual run capacitor will power both). If the capacitor burns out, the compressor may not run. To determine if the run capacitor has failed, test the capacitor with a multimeter. If the capacitor is unable to hold and release a charge or is bulging or leaking, replace it.
Less Common
05 - Carrier Central Air Conditioner Capacitor
The capacitor provides voltage to the compressor to start it. If the capacitor is defective, the compressor won't run. To determine if the capacitor has failed, test the capacitor with a multimeter. If the capacitor is unable to hold and release a charge or is bulging or leaking, replace it.
Less Common
06 - Carrier Central Air Conditioner Dual Run Capacitor
A dual run capacitor will power both the compressor and the fan motor. If the capacitor burns out, the compressor may not run. To determine if the dual run capacitor has failed, test the capacitor with a multimeter. If the capacitor is unable to hold and release a charge or is bulging or leaking, replace it.
Less Common
Frequently Asked Questions
Why is my Carrier AC compressor not running?
How do I test a Carrier AC start or run capacitor?
Could a contactor cause my Carrier AC compressor not to start?
How can I tell whether my Carrier compressor is bad or the capacitor is bad?
How do I identify the correct Carrier AC compressor or capacitor replacement part?
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