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HomeRepair HelpGrandAire Central A/C RepairGrandAire Central A/C Condensing unit does not run Repair
GrandAire Central Air Conditioner Condensing unit does not run
When your GrandAire central air conditioner condensing unit does not run, A bad run capacitor or a tripped circuit breaker or blown fuse is the most likely cause. A failed compressor is a possible but less common cause. A faulty wall thermostat may also prevent both the furnace and outdoor unit from operating. Next, check the condenser fan motor and fan motor for electrical continuity and verify that the fan blades turn freely. If the compressor and fan are not running even though the outdoor unit has power and the contactor operates, a sealed system problem, such as low refrigerant causing the low pressure switch to trip, may be responsible. A defective high or low pressure switch is less common. This can leave the AC condenser not turning on, the outdoor ac unit not running, or the condensing unit unable to start. Turn off power before inspecting panels, and leave 240V testing or component replacement to a qualified technician. Any refrigerant, pressure switch, or sealed system repair requires an EPA 608-certified, licensed HVAC technician. Enter your GrandAire model number to find the exact replacement compressor, thermostat, condenser fan motor, or other part for your specific central air conditioner.
01 - GrandAire 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 - GrandAire 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 - GrandAire 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 - GrandAire 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 - GrandAire 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 GrandAire condensing unit not turning on?
What should I check when the condenser fan is not running?
Can a thermostat cause the outside AC unit not to turn on?
Could low refrigerant or a pressure switch keep the AC condensing unit from running?
How do I find the correct GrandAire replacement part for my central air conditioner?
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