SOLVED: Why My Honeywell Thermostat Won’t Turn Off AC?

Are you facing the frustrating scenario where your Honeywell thermostat seems determined to keep your home as cold as an icebox, no matter how much you try to adjust the settings?

If your air conditioner is running continuously and you’re wondering, Why my Honeywell thermostat won’t turn off ac– you’re not alone. This common issue can lead to discomfort and increased energy bills if left unresolved.

In this troubleshooting guide, we will delve into the reasons behind this problem and provide you with step-by-step solutions to regain control of your thermostat. 

Let’s begin the journey to restore balance to your indoor climate control.

Table of Contents

10 Possible Causes Why Honeywell AC Won’t Turn Off

Before we dive into troubleshooting, it’s essential to grasp the core of the issue: why your Honeywell thermostat won’t turn off AC

This understanding will empower you to pinpoint the problem and apply the correct solution effectively. Here are some 10 common causes:

Incorrect Thermostat Settings

Ensure that the thermostat is set to the cooling mode (usually indicated by a snowflake icon) and that the temperature setting is higher than the current room temperature. Incorrect settings can keep the AC running.

Thermostat Wiring Issues

Inspect the thermostat wiring for loose or damaged connections. Poor electrical connections can disrupt communication between the thermostat and the HVAC system.

Programmed Schedule

If your thermostat has a programmed schedule, it may be overriding your desired settings. Check and reset the schedule or put the thermostat in “Hold” or “Manual” mode to maintain a constant temperature.

Dirty or Clogged Air Filter

A dirty or clogged air filter can restrict airflow, leading to the AC running continuously. Replace the air filter if it’s dirty, and remember to change it regularly.

Refrigerant Issues

Low refrigerant levels can cause the AC to run non-stop. This is a complex issue that requires a professional HVAC technician to inspect and recharge the refrigerant.

Thermostat Location

Ensure that the thermostat is installed in an appropriate location away from heat sources, direct sunlight, or drafts, as these factors can affect its accuracy.

Fan Setting

Check the fan setting on your thermostat. It should be set to “Auto” rather than “On.” Setting it to “On” will keep the fan running continuously, even when the cooling cycle is not active.

Power Cycling

Try power cycling the thermostat and AC unit. Turn off the thermostat, turn off the AC unit, wait a few minutes, and then turn them both back on.

Sensor Issues

Some thermostats have built-in temperature sensors that can malfunction. If your thermostat has a remote sensor, ensure it’s correctly placed and functioning.

Electrical or Mechanical Problems

There may be underlying electrical or mechanical issues within the HVAC system itself, such as a faulty relay or control board. These issues often require professional diagnosis and repair.

It’s important to note that these are common causes, and the specific solution may vary depending on your thermostat model and HVAC system. If you’re unsure about troubleshooting or if the problem persists, it’s best to contact a licensed HVAC technician to diagnose and fix the issue safely and effectively.

Check for User Error Honeywell Thermostat AC

Sometimes, the most common issues stem from simple user errors or oversights. Before delving into more complex troubleshooting, let’s start by double-checking your thermostat’s settings and configurations. 

Here’s a step-by-step guide to help you review and correct any potential user errors:

Thermostat Mode

Begin by verifying that your thermostat is set to the correct mode, such as “Cool” or “AC.” Ensure it’s not in “Heat” mode, as this would conflict with your desire to turn off the AC.

Temperature Settings

Examine the temperature settings on your thermostat. Confirm that the set temperature is higher than the current room temperature if you want to stop the AC. Adjust it if necessary.

Programmed Schedule

If your thermostat has a programmed schedule, ensure that the programmed cooling periods align with your preferences. Make changes to the schedule if needed.

Fan Mode

Check the fan settings on your thermostat. It should be set to “Auto” rather than “On.” Running the fan continuously can make it feel like the AC is always on.

Battery Check

If your thermostat uses batteries, make sure they are not low or depleted. Weak batteries can cause erratic behavior in your thermostat.

Lock Mode

Some thermostats have a “Lock” or “Hold” feature that prevents changes to the settings. Make sure your thermostat is not locked in a particular mode.

Temperature Differential

Verify that the thermostat’s temperature differential setting is appropriate. 

This setting determines how much the temperature can deviate from your desired setting before the AC or heating system kicks in.

Honeywell Thermostat Sensor Inspection

The accuracy of your thermostat’s temperature readings is crucial to maintaining your desired comfort level and resolving the issue of your Honeywell thermostat not turning off the AC. 

Often, this problem can arise due to malfunctioning or dirty temperature sensors. Here’s how to inspect and clean the sensors:

Locate the Sensors

Most Honeywell thermostats have a small sensor near the display or on the thermostat’s interior. 

This sensor is responsible for measuring the ambient temperature in the room.

Power Off

Before you begin, turn off the power to your HVAC system. This is a safety precaution to prevent any electrical mishaps while handling the thermostat.

Remove the Cover

Carefully remove the cover or faceplate of your thermostat to access the interior components. You may need a screwdriver to do this.

Inspect for Dirt

Examine the sensor for any dirt, dust, or debris buildup. Even a small amount of dirt can interfere with its temperature readings. 

Use a soft brush or compressed air to gently clean the sensor.

Reposition the Sensor

Check if the sensor is properly positioned. It should be level and not obstructed by any objects, such as furniture or curtains, which could affect its readings.


Some thermostats allow for sensor calibration. Refer to your thermostat’s manual to see if this is an option and adjust it if necessary.

Replace the Cover

After cleaning and inspecting the sensor, securely reattach the thermostat cover or faceplate.

Power On

Turn the power back on to your HVAC system and observe how the thermostat behaves. Make sure it accurately reflects the room’s temperature.

Troubleshooting Steps for Honeywell Thermostat Won’t Turn Off AC

If your Honeywell thermostat still won’t turn off the AC after checking for user errors and inspecting the sensor, it’s time to explore some common troubleshooting steps to resolve the issue.

These steps are designed to address a range of potential problems:

Thermostat Reset

Begin by performing a thermostat reset. This can often resolve software glitches or incorrect settings. Refer to your thermostat’s manual for specific reset instructions.

Temperature Adjustment

Double-check the set temperature on your thermostat. Make sure it’s set to your desired level and not too low, causing the AC to run continuously.

Programmed Schedule

Review and adjust your thermostat’s programmed schedule if applicable. Ensure that cooling periods align with your preferences.

Fan Settings

Verify that the fan mode is set to “Auto” rather than “On.” Keeping the fan running continuously can make it feel like the AC is always on.

Temperature Differential

Adjust the temperature differential setting, if available. A smaller differential may help prevent frequent cycling of the AC.

Check for Obstructions

Ensure that the thermostat is not obstructed by objects or furniture that could affect its temperature readings.

Firmware Update

Check if there are firmware or software updates available for your thermostat model. Updating the software can resolve known issues and improve performance.

Battery Replacement

If your thermostat uses batteries, replace them with fresh ones to rule out power-related problems.

Inspect Wiring

Carefully inspect the wiring connections at the thermostat and the HVAC system. Loose or damaged wires can disrupt communication.

Circuit Breaker Check

Confirm that the circuit breaker for your HVAC system is not tripped. Reset it if necessary.

HVAC System Inspection

If none of the above steps resolve the issue, consider inspecting your HVAC system for any malfunctions, clogs, or refrigerant issues. 

If still this issue remains It may be worth seeking professional HVAC assistance at this point.

When to Seek Professional Help?

When all else fails and your Honeywell thermostat still refuses to turn off the AC, it may be time to seek the expertise of a professional HVAC technician. 

Here’s why professional assistance can be invaluable:

Diagnosis Expertise

HVAC professionals are trained to diagnose and resolve complex issues with heating and cooling systems. 

They can quickly identify the root cause of the problem.

System Evaluation

A technician will thoroughly evaluate your HVAC system to ensure all components are functioning correctly. 

This includes checking the thermostat, wiring, sensors, and the AC unit itself.

Repair and Replacement

If a component is found to be faulty, the technician can perform the necessary repairs or recommend replacements. 

They have access to the right tools and parts for the job.

Safety Assurance

Handling HVAC systems requires knowledge of safety protocols. 

Professionals ensure that repairs are carried out safely, reducing the risk of accidents or further damage.

Energy Efficiency

HVAC technicians can optimize your system for energy efficiency, helping you save on utility bills in the long run.

Warranty Considerations

If your thermostat or HVAC system is under warranty, DIY attempts to fix the issue might void that warranty. 

A professional technician can make repairs while preserving your warranty coverage.

Peace of Mind

Hiring a professional gives you peace of mind that the issue will be resolved correctly. You won’t have to worry about recurring problems or unexpected breakdowns.

Firmware and Software Updates for Honeywell Thermostat

In the digital age, even your thermostat can benefit from software updates, much like your smartphone or computer. 

Outdated or buggy firmware can sometimes lead to issues with your Honeywell thermostat not turning off the AC. Here’s how to ensure your thermostat’s software is up-to-date:

Check for Updates

Begin by accessing your thermostat’s menu or settings. Look for an option related to software updates or firmware upgrades. 

The location of this option may vary depending on your thermostat model.

Internet Connection

If your thermostat connects to the internet, you may be able to check for updates directly through its interface. 

Make sure your thermostat is connected to your home Wi-Fi network.

Visit the Manufacturer’s Website

If you can’t find an update option on your thermostat, visit the official Honeywell website. 

Look for a support or downloads section where you can find the latest firmware or software updates for your specific thermostat model.

Download and Install

If an update is available, download it to your thermostat. Follow the on-screen instructions to install the update. 

This process may take a few minutes, so be patient.


After the update is installed, it’s a good practice to restart your thermostat. This ensures that the new software takes effect.

Observe Operation

Monitor your thermostat’s operation for a day or two after the update. Check if it now behaves correctly and turns off the AC as expected.

Energy Efficiency Tips for Honeywell Thermostat

While troubleshooting your Honeywell thermostat’s issue of not turning off the AC, it’s important to consider energy efficiency. 

Maintaining a comfortable home while minimizing energy consumption is beneficial for both your wallet and the environment. Here are some energy efficiency tips to keep in mind during this process:

Optimal Temperature Settings

Set your thermostat to a temperature that’s comfortable but not excessively low. Each degree higher can result in energy savings.

Use Programmable Thermostats

If your thermostat allows it, utilize programmable settings to automatically adjust temperatures based on your daily schedule. Raise the temperature when you’re away or asleep to reduce cooling costs.

Regular Maintenance

Schedule routine HVAC system maintenance, including cleaning or replacing air filters, checking for refrigerant leaks, and ensuring proper system operation. 

A well-maintained system operates more efficiently.

Seal Leaks and Insulate

Ensure your home is well-insulated, and seal any gaps or leaks around doors, windows, and ductwork. This prevents conditioned air from escaping and reduces the load on your AC.

Use Ceiling Fans

Ceiling fans can help distribute cool air more effectively, allowing you to set your thermostat a few degrees higher without sacrificing comfort.

Close Curtains and Blinds

During the hottest parts of the day, keep curtains and blinds closed to block out direct sunlight, reducing the need for air conditioning.


Use exhaust fans when cooking or showering to remove excess heat and humidity. This can help your AC work more efficiently.

Upgrade to Energy-Efficient Appliances

If your HVAC system or thermostat is outdated, consider upgrading to energy-efficient models. Look for units with high SEER (Seasonal Energy Efficiency Ratio) ratings.

Regularly Check Thermostat Settings

Periodically review and adjust your thermostat settings to ensure they align with your comfort needs and seasonal changes.

Consider Smart Thermostats

Smart thermostats offer advanced scheduling and remote control features, allowing you to optimize energy usage based on your daily routine.

Frequently Asked Questions (FAQs)

What should I do if my thermostat is still not working after troubleshooting?

If your thermostat issue persists, it’s advisable to seek professional HVAC assistance. A trained technician can diagnose and repair the problem.

Are there any safety precautions to follow when troubleshooting my thermostat?

Always turn off the power to your HVAC system before opening the thermostat. If you’re unsure about any steps, consult the thermostat’s manual or contact a professional.

Can I use a smart thermostat as a replacement for my Honeywell thermostat?

Yes, you can replace your Honeywell thermostat with a compatible smart thermostat. Smart thermostats offer advanced features like remote control and energy-saving capabilities.

How can I make my HVAC system more energy-efficient?

To improve energy efficiency, consider setting optimal temperature levels, sealing gaps in your home, using programmable thermostats, and scheduling regular HVAC maintenance.

Will updating my thermostat’s software solve all issues?

Not necessarily. While software updates can address some problems, issues related to wiring, sensors, or compatibility may require additional troubleshooting or professional assistance.

Can a malfunctioning thermostat increase my energy bills?

Yes, a thermostat that doesn’t function properly can lead to higher energy bills due to the continuous operation of the AC or heating system. Addressing the issue promptly can help you save on energy costs.


Remember that resolving honeywell thermostat won’t turn off AC issues often involves a combination of these steps. By following the guidance provided here, you’re well-equipped to tackle the problem and enjoy a more comfortable and cost-effective living space. 

If you’ve exhausted these troubleshooting options and the issue persists, don’t hesitate to reach out to a qualified HVAC technician for further assistance. 

Your home’s climate control is within your grasp, and with the right steps, you can achieve the ideal balance of comfort and efficiency.

Scott Maupin