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HomeRepair HelpCarrier Central A/C RepairCarrier Central A/C Condensing unit does not run Repair
Carrier Central Air Conditioner Condensing unit does not run
When your Carrier condensing unit won't start, the outdoor AC unit is not running, or the outside AC unit is not turning on, start with the compressor, the most likely cause listed for an AC condenser not turning on. A failed compressor can stop refrigerant circulation and leave the AC condenser dead, although the capacitor and condenser fan motor should be checked first by a qualified technician. Next, a faulty wall thermostat may fail to send the signal that starts the furnace and condensing unit. A defective condenser fan motor can also keep the AC condensing unit from working, especially if the fan blade does not turn freely because of seized bearings. If the unit has power but neither the compressor nor fan runs, a sealed-system problem, low refrigerant, or a tripped low pressure switch may be responsible. Pressure switch replacement requires refrigerant recovery and EPA 608 certification. Testing or replacing components inside the outdoor unit also involves 240-volt line voltage, so use a licensed HVAC technician unless you are qualified. Enter your model number to find the exact Carrier replacement part for your central air conditioner.
01 - Carrier Central Air Conditioner Compressor
Central air conditioners use a compressor to pump refrigerant through the condenser coils located in the outside condensing unit and through the evaporator coils mounted on top of the furnace or air handler. While it's not a common problem, if the compressor fails, the condensing unit will not run. You can use a multimeter to test the compressor for electrical continuity, a continuous electrical path present in the component, to help determine if the compressor is faulty. If all other potentially defective components, such as the capacitor and condenser fan motor, are operating properly, then a qualified technician should ...
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Highly Likely
02 - Carrier Central Air Conditioner Wifi Thermostat
The WiFi thermostat has contacts in it that control the furnace. If the contact fails it can result in the furnace and the condensing unit to not run at all.
Common
03 - Carrier Central Air Conditioner Condenser Fan Motor
A faulty condenser fan motor can be responsible for the central air conditioner condensing unit not running. You can use a multimeter to test the fan motor for electrical continuity, a continuous electrical path present in the motor, to help determine if the motor is defective. You can also use the multimeter to determine if power is reaching the motor. You can also try rotating the fan blades by hand. If the blades do not turn freely, it's likely the motor bearings have seized and the fan motor will need to be replaced.
Common
04 - Carrier Central Air Conditioner Fan Motor
A faulty fan motor can be responsible for the central air conditioner condensing unit not running. You can use a multimeter to test the fan motor for electrical continuity, a continuous electrical path present in the motor, to help determine if the motor is defective. You can also use the multimeter to determine if power is reaching the motor. You can also try rotating the fan blades by hand. If the blades do not turn freely, it's likely the motor bearings have seized and the fan motor will need to be replaced.
Common
05 - Sealed system problem
If the condensing unit has power to it, the contactor checks out okay, but the fan and compressor are not running, it is likely that the unit is low on refrigerant which will cause the low limit pressure switch to trip and keep the unit from running. Since diagnosing and repairing a sealed system takes specialized tools and knowledge, a qualified service technician should diagnosis and repair the unit.
Common
06 - Carrier Central Air Conditioner Pressure Switch
A pressure switch is a safety device used to help prevent component and system failures. There are basically three types of pressure switches used in central air conditioning and heat pump applications: High Limit, Low Limit, and Ambient Temperature. Depending on the model, you may have one or more of these or none. The pressure switch(es) can be checked with a multimeter, referencing the wiring diagram for the circuit locations. Note: If a pressure switch needs to be replaced the refrigerant will need to be removed, requiring a qualified technician.
Less Common
Frequently Asked Questions
Why is my Carrier AC condenser not turning on?
What should I check if my Carrier condenser fan is not running?
Could a bad capacitor or compressor cause my Carrier AC unit not to start?
Why are the fan and compressor on my Carrier condensing unit both not running?
How do I find the correct Carrier AC replacement part?
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