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HomeRepair HelpGrandAire Central A/C RepairGrandAire Central air conditioner won't turn on Repair
GrandAire Central air conditioner won't turn on
When your GrandAire central air conditioner won't turn on, start with the 24-volt control circuit before replacing condensing unit parts. The most likely cause is a failed transformer, which supplies low voltage from the furnace or air handler to the thermostat and contactor. A defective furnace control board is another highly likely cause, especially if the contactor is not receiving 24 volts or the blower motor has no power. If the thermostat display is blank, replace its batteries. Next, check for an incoming power problem, including a tripped circuit breaker, blown fuse, or power switch turned off at the furnace or air handler. Less common causes include a faulty wall thermostat or thermostat wiring, damaged thermostat wire, or a missing 24-volt signal between the C and Y terminals. This troubleshooting can help when an air conditioner is not turning on, an AC unit won't turn on, or an outside AC unit is not running. Turn off power before opening panels, and have a licensed HVAC technician handle 240-volt testing or repairs. No refrigerant work is needed for these checks. Enter your model number to find the exact GrandAire transformer, control board, thermostat, or other replacement part for your central air conditioner.
01 - GrandAire 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 - GrandAire 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 - GrandAire 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 - GrandAire 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 GrandAire central air conditioner not turning on?
How do I know if my AC thermostat is not turning on the air conditioner?
What should I check if my outside AC unit is not turning on but the thermostat works?
Can I replace a GrandAire AC transformer, thermostat, or control board myself?
How do I find the correct replacement part for my GrandAire central air conditioner?
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