UniEnergy Technologies Battery » Why My Honeywell Thermostat Not Working After Battery Change? (Fixes!!!)

Why My Honeywell Thermostat Not Working After Battery Change? (Fixes!!!)

If you are experiencing problems with your Honeywell thermostat after changing the batteries, don’t worry – you’re not alone. It has happened to others before as well. But no matter, because the good news is that there are a few fixes that you can try before calling in a HVAC technician.

In this blog post, we will walk you through some common reasons why your thermostat might not be working and how to fix it yourself. We will also provide instructions for resetting your thermostat to its factory settings if necessary. Remember, we highly recommend that you consult with a qualified HVAC technician if you are having trouble with your thermostat system.

So, to get your thermostat up and running again, let’s keep reading for all the tips and tricks!

Honeywell Thermostats Basic Information

Before we delve into troubleshooting and fixing your thermostat, let’s take a step back and review the basics of a thermostat. A thermostat is a device that controls the temperature – the heating and air conditioning in your home. It is usually mounted on a wall, usually near an entryway or window.

Thermostats come with different types of batteries, depending on the thermostat model, such as AA or AAA. Some thermostats are even considered smart thermostats, and they are hardwired directly into your home. You will want to check your thermostat’s user manual to determine what type of thermostat you have and how it works.

As far as Honeywell thermostats go, they come in many different models and sizes, but most have some features in common:

Honeywell Thermostats Basic Information
Image credit: digitaltrends.com

The Battery Compartment

This is where you will find the batteries that power your thermostat. For most thermostats, it is located on the side or back of the unit.

The Reset/Menu Button

This button allows you to reset your thermostat to its default factory settings. It is usually found next to the battery compartment on newer models.


This part covers the inner workings of the thermostat and keeps the thermostat’s components safe. It is usually made out of plastic or metal and includes a slot where you can insert your fingers to remove it from the wall.

What Type of Batteries Can I Use in my Honeywell Thermostat?

If your Honeywell thermostat isn’t working even though you changed the batteries, you may be wondering if you possibly used the wrong batteries. Well, there is good news for you. While many people use Alkaline batteries for their thermostats, you can also use Lithium-ion batteries.

In other words, you don’t have to worry about using the correct type of batteries. You’re not going to hurt your thermostat.

And as we mentioned before, different models use different sizes of batteries: AA or AAA batteries. Just check your manual if you’re confused about what type to use.

Common Reasons for Honeywell Thermostats Not Working After Battery Change

It can be frustrating when your thermostat isn’t working after a battery change, but there are a few common reasons why this happens.

Let’s look at them in more detail:

Common Reasons for Honeywell Thermostats Not Working After Battery Change

1. Replacing the Batteries Incorrectly

One of the most common reasons your thermostat might not be working is that you’ve replaced the batteries incorrectly. Make sure you securely insert the new pair of batteries so that they have a strong connection. If you haphazardly insert them in their slots and they don’t have a strong connection, then they won’t allow the thermostat to work.

2. Battery Holder Damage

It’s important to also make sure that you use the correct polarity when changing the thermostat’s batteries as well as placing them in correctly in their slots. If either of these are not done correctly, it can cause damage to the battery holder and further prevent your thermostat from working properly.

3. Blown Fuse

In some rare cases, the thermostat’s fuse may have blown due to a voltage spike caused by incorrect batteries. Check your thermostat’s user manual for instructions on how to replace the thermostat’s fuse and get it back up and running. Contact an HVAC technician if you are confused.

4. Wrong Orientation

The thermostat’s battery compartment is usually located either in the faceplate or behind an access door on the side of the thermostat. Make sure that you are placing the new batteries in correctly with the positive sides facing the correct direction, as per Honeywell support instructions.

5. Incorrect Reset

Resetting your thermostat after a battery change can be effective if done correctly. Be sure to check your thermostat’s user manual for the correct resetting instructions.

6. Honeywell Thermostat is Broken

It could be possible that your thermostat is actually broken if it has been subjected to too much heat, such as sitting near a furnace, if it it has received some damage, is faulty from the manufacturer, or is just very old. In this case, you will need to contact an HVAC technician and have them take a look at the thermostat or replace the thermostat altogether.

How to Reset Honeywell Thermostat After A Battery Change

If you have changed your thermostat’s batteries and it is still not working, then a reset might be in order. This can help clear out any old preferences or faulty settings that could be causing the thermostat to malfunction.

Resetting directions may vary between devices, but essentially, to perform a factory reset on your thermostat:

  • First, turn off the thermostat’s breaker switch and remove the thermostat battery compartment from its baseplate on the wall.
  • Remove all of the old batteries from their slots and replace them with a new pair of correctly placed batteries (check the user manual for correct type and size).
  • Some thermostats ask you to put the batteries in with the incorrect orientation and leave them that way for about 10 seconds in order to trigger the factory reset. However, if your thermostat is a touch screen, you can simply navigate to the Menu button > Preferences Menu > Restore Factory Settings > Yes

Once these steps are completed, check that the thermostat display is clear and that no fault messages are showing.

Your thermostat should now be back up and running correctly with all default factory settings in place! You can now reset your schedule.

Other Important Tips for Replacing Your Honeywell Thermostat’s Batteries

Now that you know how to reset and troubleshoot your Honeywell thermostat after a battery change, let’s recap, as well as look at some important tips to remember when replacing your thermostats batteries:

  • Use only the correct type and size of batteries as per your thermostat user manual.
  • Place the batteries in correctly with the right polarity and orientation.
  • Always replace both old batteries at the same time, even if just one has gone flat.
  • Never bang on the thermostat or use an object to lodge into your thermostat to try to get it working again. This can cause damage to the thermostat components.
  • If the thermostat is still not working after your battery change, consult a qualified HVAC technician for more advice on troubleshooting tips and solutions.

By following these steps you should have your Honeywell thermostat up and running again shortly!

Don’t Forget to Check Your Warranty!

One last important tip: It is also always a good idea to check your thermostat’s warranty before fixing or replacing anything. This is because you want to ensure that replacing the thermostat’s batteries is covered (or not) by the warranty.

Additionally, you will want to know if there are any actions you might take that would void your warranty if you’re not careful. Consulting your warranty will give you a much better idea of what thermostat problems you can fix and which ones you should leave to qualified professionals.


Now that you know how to reset and troubleshoot your thermostat after a battery change, here are some of the most frequently asked questions about Honeywell thermostats and their batteries:

Q1: Can I Replace my Honeywell Thermostat’s Batteries Myself?

Yes, replacing thermostat batteries is a fairly simple task and can usually be done by homeowners with basic tools and some patience. Be sure to carefully follow thermostat user manual instructions when replacing thermostats’ batteries to make sure they are installed correctly!

Q2: How Long Do Honeywell Thermostat Batteries Last?

Honeywell thermostat batteries typically last between two and three years, depending on thermostat model and usage. It’s best to check thermostat user manual for specific advice and instructions on battery replacement.

Q3: How Much Does an HVAC Technician cost?

The cost of an HVAC technician for thermostat repair or thermostat battery replacement can vary widely depending on thermostat type and the complexity of thermostat repairs. Usually these are quick repairs, however, so the cost isn’t astronomical. It’s best to call a local HVAC company and consult a qualified HVAC professional for an estimate before any work is done.


So there you have it – a quick guide to replacing your Honeywell thermostat’s batteries and resetting your Honeywell thermostat after the battery change. We hope this helps!

If you need any further help getting your Honeywell thermostat up and running like new, please don’t hesitate to contact the Honeywell support team for more advice and assistance with troubleshooting tips. And as always, consult a qualified HVAC technician for any repairs you need completed. Good luck!

What other questions do you have about Honeywell thermostats? Let us know in the comments below!

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