How do you get the AC to turn on?

To turn on the AC, switch on the thermostat or remote, set the mode to cooling, and choose a comfortable temperature, while ensuring the system has power and there are no tripped breakers.

Know your system

Central air conditioning

Central A/C is controlled mainly through a thermostat and the outdoor condenser. Here’s how to get it running quickly when you expect cool air to flow inside your home.

1. Confirm the thermostat and furnace/air handler have power. If the thermostat runs on batteries, replace them or ensure it is connected to power.


2. Check the circuit breaker labeled for the air conditioner and the outdoor disconnect to make sure they are ON and not tripped.


3. Set the thermostat to Cool mode, select Auto fan, and choose your desired temperature.


4. Review any economizer or humidity settings that might delay cooling from starting.


5. If you use a smart thermostat, verify Wi‑Fi connectivity and that the app isn’t enforcing a delay or schedule.


6. Listen for the outdoor condenser to engage; if you don’t hear a click or feel airflow after a minute, there may be a hardware issue requiring service.

If these steps don’t initiate cooling, there could be a compressor, refrigerant, or control fault that needs professional inspection.

Window and portable air conditioners

Window units and portable ACs are self-contained but still require correct setup and power to start cooling.

1. Turn on the unit using its built‑in switch and ensure it’s plugged into a functioning outlet.


2. Set the mode to Cool and adjust the temperature to your target level.


3. Make sure the exhaust hose is properly vented to the outside and not kinked or blocked.


4. For portable units, verify any condensate reservoir or tray isn’t full and that drainage is configured if required.


5. Use the remote control or control panel to confirm cooling is active and adjust as needed.


6. If the unit still won’t respond, test the outlet with another device or try a different circuit.

Proper venting and drainage are essential for window and portable units to operate reliably and safely.

Smart and app-controlled systems

Many newer models use smart thermostats or built‑in Wi‑Fi controls, which rely on network connectivity and account permissions.

1. Open the AC control app or your smart thermostat app and select the device you want to power on.


2. Tap Power On or set mode to Cool, then specify the desired temperature and fan setting.


3. Confirm the device is connected to Wi‑Fi and that the account is active.


4. If using voice control, ensure the voice assistant has access to the device and that any routines are configured correctly.


5. Check for any scheduling or energy-saving modes that might delay immediate startup.

Smart controls offer convenience but depend on connectivity and proper account setup; review both if the unit won’t turn on.

Troubleshooting: if the AC still won’t turn on

When a unit fails to start, perform these basic power and control checks before seeking professional help.

• Test the wall outlet or power strip with another device to confirm power is available.


• Check the thermostat or remote batteries and replace them if needed.


• Inspect the circuit breaker and outdoor disconnect for trips or faults; reset if safe to do so.


• Ensure no safety switches (like condensate switches) have tripped or are stuck in a closed position.


• Review any error codes on the thermostat or control panel and consult the manual for meaning and remedies.

If problems persist, contact a licensed HVAC technician to diagnose electrical, refrigerant, or compressor issues and prevent further damage.

Maintenance tips to prevent startup problems

Regular upkeep helps ensure the AC turns on reliably and runs efficiently when you need it.

• Replace or clean air filters every 1–3 months, depending on use and manufacturer guidance.


• Clean the outdoor condenser coils and remove debris around the unit to maintain airflow.


• Ensure clear airflow around indoor vents and outdoor condenser and remove obstructions.


• Test the thermostat periodically and replace batteries as needed; consider upgrading to a programmable or smart thermostat for reliability.


• Schedule professional service annually for inspection, refrigerant checks, and overall system health.

Regular maintenance reduces the likelihood of startup issues and improves energy efficiency and comfort.

Summary

Turning on an air conditioner is a straightforward task when you know your system: power it on, select Cool mode, and set a comfortable temperature, while ensuring proper power supply, venting, and connectivity where applicable. Whether you’re dealing with central, window, portable, or smart cooling, the core steps are consistent: verify power, choose cooling, and confirm any system-specific requirements. If startup problems persist, professional service is recommended to diagnose electrical, refrigerant, or control issues and restore reliable cooling.

How do I reset my air conditioner?

To reset an AC unit, turn off the power at the thermostat and circuit breaker, wait for at least one minute, and then restore power, starting with the breaker. If your unit has a physical reset button, locate it on the outdoor unit (often behind a panel) and press and hold it after cutting the power, then turn the power back on. 
Resetting using the circuit breaker
This method is best for central air conditioning units and is the standard approach if no other reset button is present. 

1. Turn off the thermostat: Set your thermostat to the "off" position to stop the cooling cycle. 
2. Turn off the circuit breaker: Go to your home's breaker box and switch the breaker labeled for your AC unit to the "off" position. 
3. Wait for the system to reset: Give the unit about 5 minutes to completely power down. 
4. Restore power: Turn the circuit breaker back on. 
5. Turn the thermostat back on: Set your thermostat back to the "cool" setting to restart the unit. 

Resetting using the reset button
This is an option for units that have a specific reset button, often found on the outdoor unit. 

1. Turn off the thermostat: Set your thermostat to "off". 
2. Turn off the circuit breaker: Go to the breaker box and switch the AC's breaker to "off". For safety, unplugging the unit directly from the outlet is another option for window units. 
3. Locate the reset button: This is often a small, red or black button located near the compressor on the outdoor unit, sometimes behind a removable service panel. 
4. Press and hold the button: Press and hold the reset button for at least 5 seconds. 
5. Restore power: Turn the circuit breaker back on or plug the unit back in. 
6. Turn the thermostat back on: Set the thermostat to "cool" to see if the unit is working properly. 

If problems persist
If the reset doesn't resolve the issue, there may be a more serious problem. Check for any obvious issues like a tripped breaker or debris around the outdoor unit, but if the unit still malfunctions, contact a licensed HVAC professional for assistance. 
57sHow to Reset Your HVAC System (2 Easy Methods You Can Do Yourself ...YouTubeHVAC Bee · 2w 55sHow to Reset your HVAC SystemYouTubeAllTech Services · 5mo 0:06Window AC unit immediately turns off after it resets : r/fixitRedditdermatology4lyfe · 2y 0:34How to reset your Air Conditioner Circuit BreakerYouTubeAccess Heating, Air conditioning & Plumbing · 5y (function(){
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How do I get my AC to kick on?

To get an AC to work, first check the thermostat to ensure it's set to "cool," the temperature is low enough, and the batteries are fresh. Next, look at the circuit breaker for your HVAC system and reset it if it has tripped. Finally, clean or replace the air filter, as a clogged filter is a common cause of AC issues. 
This video demonstrates how to check and reset your AC system's circuit breaker: 50sHVAC BeeYouTube · Feb 13, 2025
Thermostat and power

• Check settings: Make sure the thermostat is set to "cool" mode and the desired temperature is lower than the current room temperature. 
• Replace batteries: If the thermostat is blank or unresponsive, replace the batteries. 
• Reset the system: Turn the thermostat to "off," go to the electrical panel, and flip the AC's circuit breaker off and then on again. 
• Check other switches: Ensure any disconnect switches on the outdoor unit are on. 

This video explains how to diagnose and fix common AC problems, including a dirty filter: 59sThe DIY HVAC GuyYouTube · Mar 1, 2023
Airflow and filters

• Replace the air filter: A dirty or clogged air filter restricts airflow, making the AC work harder and potentially freeze up. A clean filter is crucial for proper function. 
• Check vents: Make sure the air vents in your home are open and not blocked by furniture or other objects. 
• Clear debris from the outdoor unit: Check the area around your outdoor unit and clear away any leaves, grass clippings, or other debris that may be blocking the vents. 

This video shows how to inspect and clean the outdoor AC condenser coils: 59sFix This HouseYouTube · Aug 11, 2024
Next steps if the problem continues

• Look for ice: If you see ice on the evaporator coils, turn off the AC and let it defrost completely before trying again. 
• Check the condensate drain: Ensure the condensate drain line for your indoor unit is not clogged, as a blockage can cause a safety switch to shut the system down. 
• Call a professional: If these steps don't fix the issue, there may be a more serious problem, such as a bad capacitor, a refrigerant leak, or a faulty motor. It is best to contact a professional HVAC technician for further assistance. 

How do I fix my AC not turning on?

To troubleshoot an AC that won't turn on, first check the thermostat settings and circuit breakers, then inspect the air filter and outdoor unit for clogs or debris. If the issue persists, examine the condensate drain line for clogs and look for signs of ice build-up, which can indicate other problems like low refrigerant.
 
This video explains common reasons why an AC might not turn on: 47sAC Service Tech LLCYouTube · May 28, 2022
Power and thermostat checks

• Check the thermostat: Ensure it's set to "Cool" and the temperature is lower than the current room temperature. Replace the batteries if they are low or dead. 
• Reset the circuit breaker: Find your electrical panel and reset any tripped breakers for the AC unit. Flip it to the "off" position first, then back to "on". 
• Check the power switch: Make sure the disconnect switch on the outdoor unit is in the "on" position. 

This video shows how to check the circuit breaker and other simple fixes: 1mWord of Advice TVYouTube · May 28, 2018
Airflow and drainage checks 

• Inspect the air filter: A clogged air filter can cause the system to freeze or fail. Check and replace or clean the filter if it's dirty. 
• Clear the condensate drain line: A clogged drain line can cause water to back up and trigger a safety switch. Check for and clear any blockages in the line. 
• Clean the condenser unit: Clear any leaves, dirt, or other debris from the outdoor condenser unit's fins to ensure proper airflow. 

This video demonstrates how to inspect and clean an AC unit: 1mWord of Advice TVYouTube · Jul 26, 2024
Other potential issues

• Look for ice: Check the evaporator coils for ice, which can indicate a problem with airflow or refrigerant. If you find ice, turn the AC off and let it thaw completely before turning it back on. 
• Listen for unusual noises: Listen for sounds like buzzing or grinding, which could signal a failing capacitor or motor. 
• Check for blown fuses or wiring issues: If you have a blown fuse, replace it. For more complex issues like loose or frayed wiring, it's best to call a professional. 

This video discusses how a faulty capacitor can cause an AC to fail: 57sWord of Advice TVYouTube · Jul 10, 2017

How do I turn the AC on?

To turn on the AC, first locate your thermostat or the unit's manual controls. For a thermostat, move the system switch to "Cool" and set the temperature lower than the current room temperature. For a split AC unit, you may need to open the front panel to find a manual "on/off" or "dip" switch, typically on the right side, and use a non-conductive object to press it once the main power is on.
 
For central air conditioning

1. Adjust the thermostat: Find the mode switch on your thermostat and set it to the "Cool" setting. If it was off, you may need to move it from "Off" to "Cool". 
2. Set the temperature: Turn the temperature down to a setting that is a few degrees colder than the current indoor temperature. This will signal the system to start. 
3. Check the system: Go outside to the outdoor condenser unit. You should hear the fan running. Go back inside and feel the vents to confirm cold air is coming out. 

This video demonstrates how to check if the AC is working correctly: 54sAny Hour Services - Electric, Plumbing, Heating & AirYouTube · May 6, 2023
For a split AC unit

1. Locate the power switch: Open the front panel of the indoor unit. There is often a small "on/off" switch on the right-hand side. 
2. Power on the unit: Make sure the main power is on (this may be a circuit breaker) and use a non-conductive object, like a pen, to gently press the "on/off" switch. 
3. Close the panel: Close the front panel of the unit. The AC will turn on to a default setting, usually around 24−25∘24 minus 25 raised to the composed with power24−25∘C in cool mode.