Understanding the Error: Why Your Honeywell Thermostat Displays “AC Power Loss”

Stuart Williams
By Stuart Williams 10 Min Read
10 Min Read
what does it mean when your honeywell thermostat says ac power loss featured

When your Honeywell thermostat displays the message “AC Power Loss,” it means there’s a temporary loss of power to the HVAC system. Check nearby circuit breakers to see if any have been tripped. Reset them if needed, and inspect the electrical connections between the thermostat and the HVAC system.

Any loose or damaged wires should be reconnected or replaced. If these steps don’t work, consult a professional technician to diagnose and repair any underlying electrical problems.

Power outages occur, but when the thermostat says ‘AC Power Loss,’ it’s like the HVAC system yelling, ‘Abort mission! I repeat, abort mission!’

Understanding the “AC Power Loss” message

To understand the “AC Power Loss” message on your Honeywell thermostat, let’s delve into the section about understanding it. We’ll explore what causes this message to appear, shedding light on possible solutions.

What causes the “AC Power Loss” message to appear on a Honeywell thermostat

The “AC Power Loss” message on your Honeywell thermostat means there’s a disruption to the power supply. This could be a power outage, tripped circuit breaker, or faulty power cord.

Check the circuit breaker panel to make sure the thermostat’s breaker isn’t tripped. Reset it if it is. Also, check that the power cord is plugged in securely to both the thermostat and outlet.

If the message keeps appearing, the wiring or thermostat may be the problem. It’s best to contact a professional technician for help.

The message gives users info about their thermostat’s status and potential issues. Knowing what causes the message helps homeowners maintain their heating/cooling systems. To fix it, just pray to the tech gods!

Troubleshooting steps

To troubleshoot the “AC Power Loss” message on your Honeywell thermostat, follow these steps: Check the power source, verify the wiring connections, and reset the thermostat.

Step 1: Check the power source

Checking the power source is key to the smooth running of any device.

  1. Inspect the power cord for any signs of damage or loose connections. Make sure it is plugged in securely.
  2. Try another device in the outlet to see if the issue lies there. If using a laptop or mobile device, use a different charger or USB lead.
  3. If no luck, use another power source, such as a different socket or a generator. Always follow manufacturer guidelines and contact technical support if needed.
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I learnt this the hard way after my laptop suddenly shut down whilst working on a project. It was the faulty charger that was the issue. Replacing it fixed the problem and I was able to carry on.

Keep this in mind: Step 1 – Check the power source – can save time and help fix issues quickly.

Step 2: Verify the wiring connections

To ensure successful Step 2: Verify the wiring connections, take these 6 guide steps:

  1. Inspect connectors for cleanliness and secure attachment.
  2. Check for broken or loose wires that may cause problems.
  3. Use a multimeter to check voltage and continuity.
  4. Check the wiring diagram for proper polarity.
  5. See if any wires are overheating or have melted insulation.
  6. Double-check that all connections match the color codes or labels.

In addition to these steps, check for any special features specific to your system. For example, special grounding or compatibility with other equipment.

Carrying out Step 2 carefully will help you avoid malfunctions and troubleshoot problems. It’s important not to miss this step – saving you costly repairs or downtime.

Verify all wiring connections thoroughly to ensure a smooth operation! Resetting attitudes is not as easy as resetting a thermostat.

Step 3: Reset the thermostat

Resetting your thermostat can fix many HVAC system issues. Here’s a 3-step guide to help:

  1. Locate the thermostat on the wall. Look for a “reset” or “restart” button, maybe hidden behind a cover or in a menu.
  2. Press and hold the reset button for 5-10 seconds. This will restart the thermostat and clear any temporary errors.
  3. Give your thermostat a few minutes to reboot. Avoid adjusting settings or turning off power during this time.

For best results:

  • Check the thermostat has new batteries. Low battery levels can cause problems and stop the reset.
  • Make sure wires and connections are secure. Loose connections can disrupt communication between the HVAC system and thermostat.
  • Update the thermostat’s firmware if available. Software updates can fix bugs and improve performance.

Follow these steps and suggestions for the best chance to reset your thermostat and get your HVAC system running optimally. Plus, patience is key. A decade or two should do the trick!

Additional considerations

To address additional considerations in dealing with your Honeywell thermostat’s “AC Power Loss” message, we’ll discuss common issues that may trigger this message and when to seek professional help. By understanding these sub-sections, you’ll be equipped with the necessary knowledge to troubleshoot the problem yourself or determine when a professional technician should be called.

Common issues that may trigger the “AC Power Loss” message

The “AC Power Loss” message might result from a lot of causes. These can disrupt the power and make daily life difficult. Things to consider:

  • Wiring: Old or wrongly installed wiring can result in power loss. Make sure your electrical system is up to date and in working condition.
  • Circuit breaker: A tripped breaker could cause the AC power loss message. Check your circuit breaker panel and reset any tripped breakers.
  • Power surges: Surges in power can overload your electrical system, causing it to shut down. Invest in surge protectors to help stop this.
  • Cords: Frayed or damaged cords can affect the electricity, causing power loss. Inspect your cords often for any wear and tear.
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Besides these common causes, faulty AC units or electric grid issues could trigger the “AC Power Loss” message. Stay alert and get expert help if needed.

Factoid: According to Energy.gov, power outages cost the U.S. economy an estimated $150 billion every year! When it feels like a horror movie, it’s time to call the professionals.

When to seek professional help

When tough times come, you must know when to get help from a professional. Expert advice can give valuable support and understanding, assisting people with getting past their troubles. Whether it be mental health problems or issues with relationships, talking to an expert can make a huge difference in one’s well-being.

It is key to get help from a professional when constantly feeling down or anxious, and it interferes with everyday life. Mental health experts are trained to identify why someone has these feelings and provide solutions. Also, if arguments in relationships keep happening or get worse, a therapist or counsellor can help. They can give new perspectives and teach how to communicate better.

Getting help from a professional is also necessary for substance abuse or addiction. Qualified professionals have the skills to guide individuals through this hard process. Their support is important in taking control back over one’s life and stopping negative behaviour.

Research by the American Psychological Association shows that more adults are seeking help for mental health issues these days. The opinion that mental health is something to be ashamed of is slowly going away, as more people understand how important it is to talk to a trained professional.


Your Honeywell Thermostat’s “AC Power Loss” message is important. Loss of AC power can disrupt your thermostat and require troubleshooting or help.

When the thermostat shows this message, it means there was an electrical power interruption to the thermostat. Reasons could be a power outage, circuit breaker tripped, or wiring issue.

Check if there’s a power outage in your area. If not, look at the circuit breaker connected to your HVAC system. Check wiring connections inside the thermostat for loose or damaged wires.

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Repairs beyond basic troubleshooting can be dangerous. Mishandling electrical components can cause more damage or electric shock.

The importance of this issue is clear. Thermostats with AC power give users better control. But electricity disruptions can happen.

Manufacturers like Honeywell show users ‘AC Power Loss’ messages to diagnose and help them. This helps customers be aware of issues fast and encourages them to get help from experts.

Frequently Asked Questions

1: What does it mean when my Honeywell thermostat says "AC Power Loss"?

When your Honeywell thermostat displays the message "AC Power Loss," it indicates that the thermostat has lost power from the electrical source it is connected to.

2: Why does the thermostat show "AC Power Loss"?

The "AC Power Loss" message on your Honeywell thermostat usually appears when there is a disruption in the power supply. This could be due to a power outage, a tripped circuit breaker, or a loose electrical connection.

3: How can I fix the "AC Power Loss" issue on my Honeywell thermostat?

To fix the "AC Power Loss" problem, first, check if there is a power outage in your area. If there is no outage, ensure that the thermostat is securely connected to its power source and that the circuit breaker is in the "On" position. If the issue persists, consider contacting a professional electrician or HVAC technician for assistance.

4: Will my thermostat settings be lost when it shows "AC Power Loss"?

In most cases, your thermostat settings will not be lost when the display shows "AC Power Loss." Honeywell thermostats are designed to retain their programming and settings even during power interruptions. However, if the power loss is prolonged or the thermostat's internal battery is low, your settings may be reset to default.

5: Can a "AC Power Loss" message affect the functioning of my HVAC system?

If your Honeywell thermostat displays "AC Power Loss," it does not necessarily mean that your HVAC system is affected. The message is simply an indication that there is a disruption in the thermostat's power supply. However, if the power loss is prolonged and affects the functioning of other electronic components, it may indirectly impact your HVAC system.

6: Should I be concerned if the "AC Power Loss" message is displayed on my thermostat frequently?

If you notice the "AC Power Loss" message frequently appearing on your Honeywell thermostat, it might be worth investigating the underlying cause. Frequent power losses can be a sign of a malfunctioning electrical connection or a larger electrical issue. Consider contacting a professional to diagnose and resolve the problem to avoid potential damage to your thermostat or HVAC system.

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Stuart Williams is an experienced author with over 8 years in the product review industry. Passionate about writing and exploring diverse subjects, he diligently conducts in-depth research to create insightful content. Stuart's expertise shines through his comprehensive reviews, detailed comparisons, informative how-to guides, and curated best lists.
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