Press the reset button. Most models require you to hold the button down for 3-5 seconds before releasing. Restore power to your AC. Restore power to the unit at the circuit breaker, and make sure the unit is set to “on” and your thermostat is set to “cool.”
Use the Reset Button on AC Unit
Don't worry; the reset button might be able to solve the issue after a sudden disconnection or power outage. You can press the “Reset” button on the air conditioning unit, often shown as a small red button, to bring your air conditioning unit back to life.
Shut off your system by hitting the isolation switch, wait 30 to 60 minutes and then turn it back on. This manual reboot fully disconnects your AC unit from power, allowing all electrical components to reset.
As mentioned, one of the more common reasons for an AC unit needing a reset is due to the protection circuit breaker inside the unit kicking in. This usually happens after a power outage occurs, and this failsafe is in place to prevent fires and explosions from occurring from a power surge.
Check the thermostat
You should check if it's been set to the correct temperature and also make sure it's set to “cool”. If the AC settings are not right, it won't turn on. You can also check if the batteries in the thermostat are fresh and replace them if needed.
Inspect for leaks or low refrigerant levels; if you suspect a refrigerant issue, a professional will need to refill and fix the leak. Call a professional if the AC is running but still not cooling properly, or if it completely stops working.
Check Your Circuit Breaker
Locate your main circuit breaker and switch it back to the "On" position. Wait 30 seconds and turn on your air conditioner again. If it still doesn't work, you'll need to call a professional for help.
Check these issues when the unit won't kick on: Check the thermostat and adjust the settings if it isn't set to Cool and an appropriate temperature setting to call for cooling. Examine the house circuit breakers for the AC unit and reset any tripped breakers. Check the air filter and replace the filter if it's dirty.
It's a small, red button usually located on or around the unit. The button should have a clear 'reset' label. Once you find the button, press it for around three seconds and observe the AC. Check whether the AC kicks on immediately and if it doesn't, press the button again for another three seconds.
If you think your air conditioner has blown a fuse, the first sign you'll notice is that the outside AC unit is inoperable. The best way to check for a blown fuse is by using a voltmeter. Be warned — you are working with live electricity and should use extreme caution when troubleshooting your system.
First, check your filters and coils for dirt and debris that may be impeding airflow. Once you've cleaned the filters and coils, run the air conditioner with just the fan so that the ice accumulation can melt off. If the AC still doesn't blow cold air, it could be that refrigerant levels are too low.
In most cases, the small red reset button is inside the AC's compressor. If unsure, you can always refer to the user's manual to find the exact location.
In AC systems, the air conditioner reset button is on the outside unit's lower edge, typically close to the ground. Some models have the reset button located behind the service panel, which may require tools to remove. Reset buttons are usually red or yellow with a clear “reset” label.
Circuit breakers can be found in homes, businesses, and industrial facilities. They are typically located in the main electrical panel, which is typically located in the basement or garage.
When you notice that your air conditioner isn't cooling, your first action should be to turn it off. This might seem counterintuitive—after all, you want your home to be cool. However, continuing to run an AC that isn't effectively cooling can cause further damage to the system.
Most modern thermostats will have a clearly marked reset button inside the panel. It's usually small and recessed, so you might need a pointed object like a paperclip to press it. For those wondering specifically how to reset air conditioner thermostat models, the process is generally the same.
Make sure the outside unit is turned on (there's probably a switch near the unit). If the outside unit has a separate circuit breaker, check your circuit box and make sure it hasn't been tripped. A more serious issue if the outside air conditioning unit's not working is a broken compressor, capacitor or fan.
Blowing the fuse cuts the power to the unit to prevent electrical damage. If your AC has shut down and won't start again, especially if you've noticed odd electrical behavior immediately before the shutdown, chances are the fuse has done its job and will need to be replaced.
The short answer: Definitely not. (Unless you have manually engaged your outside fan to run constantly, but it shouldn't be running for hours on it's own.) If your HVAC is functioning correctly, it should keep your house cool by cycling on for 15-20 minutes at a time—with distinct pauses in between each cycle.