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HomeRepair HelpA/C RepairAir conditioner wall thermostat not working properly Repair
Air conditioner wall thermostat not working properly
If your air conditioner wall thermostat is not working, start with the thermostat itself. A standard wall thermostat or WiFi thermostat controls the 24-volt signal that tells the air conditioner, furnace, air handler, or heat pump when to run. If the thermostat display is blank, the thermostat is receiving power but will not respond, or the thermostat is not controlling the air conditioner in the correct mode, the thermostat may need to be replaced. For battery-powered models, check the wall thermostat batteries next, since weak or dead batteries can make an AC thermostat not working look like a bigger system failure. If the thermostat checks out, the problem may be a failed control board that is not sending voltage to the thermostat, an incoming power problem such as a tripped breaker or blown fuse, or a bad transformer with no 24-volt output. Once you identify the failed part, enter your air conditioner model number on RepairClinic.com to find the exact wall thermostat, WiFi thermostat, control board, transformer, or related replacement part for your specific unit.
01 - Air Conditioner Wall Thermostat
The wall thermostat is responsible for controlling components and regulating the home's temperature. The thermostat can be powered with 24 volts from a control board on a separate unit, like a furnace or air handler, or from batteries in the thermostat itself. The thermostat also has terminals to receive and distribute low voltage 24 volt power to run different HVAC products such as a furnace, air conditioner, or heat pump. If the wall thermostat is receiving power but the display is dead, or it will not send power out in the appropriate modes, the wall thermostat will need to be replaced.
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Highly Likely
02 - Air Conditioner Wifi Thermostat
The WiFi thermostat is responsible for controlling components and regulating the home's temperature. The thermostat is usually powered with 24 volts from a control board on a separate unit like a furnace or air handler. The thermostat also has terminals to receive and distribute low voltage 24 volt power to run different HVAC products such as a furnace, air conditioner, or heat pump. If the WiFi thermostat is receiving power but the display is dead, or it will not send power out in the appropriate modes, the WiFi thermostat will need to be replaced.
Highly Likely
03 - Wall Thermostat Batteries
Most wall thermostats are either powered by an enclosed battery or by the air conditioner's control board. 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 - Air Conditioner Control Board
The control board regulates the power supply to all of the components in the system. If the control board fails, it might not send voltage to the thermostat, leaving the thermostat inoperable.
Less Common
05 - Incoming Power Problem
Check to see if there is power to the air conditioner. One or more indicator lights on the control board should be illuminated. If there is no power to the air conditioner, check to see if a circuit breaker has tripped or a fuse has blown. Confirm the unit is plugged in and has power.
Less Common
06 - Air Conditioner Transformer
On some air conditioning units the control board sends a low voltage signal of 24 volts to the thermostat. When the thermostat's contacts close, a 24 volt signal is sent to the appropriate unit and components. Some air conditioners may have a separate transformer for the 24 volt circuit. If the transformer has the proper input power but no 24 volt output to the thermostat, the transformer will need to be replaced.
Uncommon But Possible
Frequently Asked Questions
Why is my air conditioner wall thermostat not working and the display is blank?
Can a bad thermostat keep my AC from turning on?
What should I check before replacing an AC thermostat?
How do I know if the air conditioner transformer is bad?
How do I find the right replacement wall thermostat, WiFi thermostat, control board, or transformer?
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