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HomeRepair HelpNutone Central A/C RepairNutone Central air conditioner won't turn on Repair
Nutone Central air conditioner won't turn on
If your NuTone central air conditioner won't turn on, the most likely cause is a failed transformer, which supplies the 24-volt control signal that tells the contactor to start the outdoor condensing unit. A defective furnace control board is another possible cause, especially if the contactor is not receiving 24 volts or the furnace blower motor has no power. Next, check the wall thermostat batteries if the display is blank, then verify incoming power to the furnace or air handler by checking for a tripped circuit breaker, blown fuse, or power switch that is turned off. A failed wall thermostat or thermostat wiring is less common, but either can prevent the cooling signal from reaching the contactor through the yellow thermostat wire. This troubleshooting involves low-voltage controls, but testing or repairing the 120/240-volt circuit, disconnect box, or other line-voltage parts should be handled by a qualified technician. Turn off power before inspecting components, and never work inside the condensing unit while energized. Enter your NuTone central air conditioner model number to find the exact transformer, control board, thermostat, or other replacement part for your system.
01 - Nutone Central Air Conditioner Transformer
The furnace control board sends a low voltage signal of 24 volts to the thermostat. When the themostat cooling contacts close, a 24 volt signal is sent to the contactor coil, closing the high voltage circuit and sending power to the condensing unit components. Some furnaces have a separate transformer for the 24 volt circuit, so if the contactor is not receiving the proper voltage when the thermostat cooling contacts are closed, it's likely this transformer has failed and the component will need to be replaced.
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Highly Likely
02 - Nutone Central Air Conditioner Control Board
If the central air condensing unit contactor is not receiving 24 volts or power is not getting to the furnace blower motor, a possible cause is a defective furnace control board. While this is not a common problem, if all other potentially faulty components are working properly, the control board should be replaced.
Highly Likely
03 - Wall Thermostat Batteries
Most wall thermostats are either powered by an enclosed battery or by the furnace or air handler transformer. If the thermostat display is dead, you can remove the thermostat cover and look for replaceable batteries. Replace the batteries if needed and check operation.
Common
04 - Incoming Power Problem
Check to see if there is power to the furnace or air handler. One or more indicator lights on the control board should be illuminated. If there is no power to the furnace or air handler, check to see if a circuit breaker has tripped or a fuse has blown. Confirm the power switch on the side of the unit is turned on.
Common
05 - Nutone Central Air Conditioner Wall Thermostat
The furnace control board sends a low voltage signal of 24 volts to the contactor through the wall thermostat. When the contactor receives the signal from the wall thermostat, it closes the circuit, sending voltage to the condensing unit components. There should be 24 volts between the common (“C”) and yellow (“Y”) thermostat wire terminals on the furnace control board when the wall thermostat is in the cooling mode. You can check for this voltage with a multimeter. If voltage is not reaching the contactor, it's likely the wall thermostat is defective and will need to be replaced.
Less Common
06 - Nutone Central Air Conditioner Wifi Thermostat
The furnace control board sends a low voltage signal of 24 volts to the contactor through the WiFi thermostat. When the contactor receives the signal from the WiFi thermostat, it closes the circuit, sending voltage to the condensing unit components. There should be 24 volts between the common (“C”) and yellow (“Y”) thermostat wire terminals on the furnace control board when the WiFi thermostat is in the cooling mode. You can check for this voltage with a multimeter. If voltage is not reaching the contactor, it's likely the WiFi thermostat is defective and will need to be replaced.
Less Common
Frequently Asked Questions
Why is my NuTone central air conditioner not turning on?
What should I check if my NuTone thermostat is not turning on the AC?
Why is my outside AC unit not turning on when the thermostat is calling for cooling?
How do I test the NuTone AC transformer or control board when the unit will not start?
How do I find the correct NuTone central air conditioner part for my repair?
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