Honeywell Thermostat Not Working After Battery Change [Fixed]

If your thermostat stops working after a battery change, it can be frustrating. In this guide, I will provide solutions to common problems and help you troubleshoot the issue to get your thermostat working again.

A Honeywell thermostat not working after battery change could be caused by misplaced batteries, programming that has been reset or a faulty thermostat.  Fixing this problem may include checking if batteries were placed according to their respective terminals or reprogramming your thermostat.

In the following chart lets take a quick look at what can prevent your thermostat from working replacing the batteries.

What can stop the thermostat from working after replacing batteries?

Possible causeFixed
Batteries Wrongly  PlacedCheck terminals & insert them correctly
Lost  Schedules and programs Reprogram thermostat
Dirty terminalsClean battery terminals
Faulty thermostatCall support or have it replaced
Blown fuseReplace  5amp fuse
No voltage from the transformerTest R and C for voltage

Read also: How To Change Battery In Honeywell Thermostat So Quickly

Batteries not inserted correctly

Double-check that the batteries were inserted correctly, with the positive and negative ends facing the right direction., this may not sound  brainer  but it happens more than you think. Also check if  they are securely in place.

Lost Schedules and programs 

 Some Honeywell thermostats will display a low battery warning before the batteries completely die. If you ignored the warning and didn’t replace the batteries soon enough, the thermostat may have lost its programming or setting after they completely died.

Another problem that can cause your thermostat to lose schedules and programs is the tie taken to swap batteries. If you want to keep the settings, programs and schedules, swap the batteries within 10 seconds. 

Read also: Honeywell Thermostat Pro Series Not Cooling [Fixed]

That means you should have the new batteries at  hand when you are removing the old batteries.

 Sometimes, after a battery change, a Honeywell thermostat needs to be restarted to work 


So try restarting your thermostat and see if that works.

Dirty battery contacts

 Some batteries can leak. If your old batteries stayed in that thermostat for a really long time they would have leaked and possibly created rust. 

And that’s where a lot of problems come in. That can block voltage from new battery terminals to the contacts.

 So just make sure where the batteries make contact are free from crud. You can even use a small wire brush to  lightly clean the contacts.

Blown fuse

A blown fuse is also another possible reason your honeywell thermostat is not working after replacing the batteries. 

There may  have been a short circuit or a power surge and possibly blew up one or more fuses. 

This can cut power to your system. This can make you confuse the problem with low batteries.  So you can take a look at the furnace control board and test them for continuity if you can.

If you are uncomfortable going that far. Possibly make an appointment with a local licensed professional 

Check the switch on the side of the furnace (most have a screw in fuse built in) 

No voltage from transformer

If the thermostat was working before and just went blank suddenly, it could also be that there is just no voltage from the transformer.

The thermostat mainly works with 24 volts from the wires and batteries are back to retain settings and schedules  power outages. You can test power from the transfor by using a multimeter.

 You are going to test between the C and R terminal. If there is no voltage then not sending voltage, it may seem as if the battery is the one causing the issue. 

Under normal circumstances the voltage between these two wires  is around 24 voltage but can be anything from 8–30.

Read also: How To Change a Honeywell Thermostat From Celsius to Fahrenheit In Seconds

Open Furnace Door

If there isn’t power coming to your HVAC systems at all you  might also want to take a look at the furnace door. 

 Check to see if the bottom blower door is secure (most have a safety switch in the lower door frame) the newer furnaces have circuit boards that display a light if it has power. 

Because furnace doors are equipped with safety switches, they can cut power to your entire system. That is a possible reason  your honeywell thermostat is not working.

Damaged or Faulty thermostat

 If none of the above solutions work, there may be a fault in the thermostat.

One important thing to note is that make sure you don’t damage the little pins if you have the kind that snap on a subbase. 

 If everything else seems good, it is perhaps a good idea to contact support before thinking about replacing possible replacement( especially if you are still under warranty)


 Can I use rechargeable batteries in my Honeywell thermostat?

 Honeywell recommends using alkaline batteries with their thermostats for optimal performance. While rechargeable batteries may work, they may not last as long or provide consistent voltage.

 How often should I replace the batteries in my Honeywell thermostat?

Honeywell recommends replacing the batteries in their thermostats once a year, or when the low battery indicator appears.

 What should I do if my Honeywell thermostat is still not working after trying these solutions?

 If your Honeywell thermostat is still not working after checking the batteries, cleaning the terminals, and trying to restart it, you may need to contact Honeywell customer support or a licensed professional for assistance.

Can a power surge cause my Honeywell thermostat to stop working?

Yes, a power surge can damage the internal components of your thermostat and cause it to stop working.But  systems these days are equipped with fuses that protect them from power surges.

 Do I need to reprogram my Honeywell thermostat after replacing the batteries?

In some cases, you may need to reprogram your Honeywell thermostat after replacing the batteries, especially if the batteries were completely dead for a long time.

 However, if you replaced the batteries quickly and your thermostat still has its programming and settings, you may not need to reprogram it.

Final thoughts

After going through the various possibilities that can cause a Honeywell thermostat to stop working after a battery change, it is clear that this issue can be quite frustrating. However, it is important to remain calm and follow the troubleshooting steps outlined in this guide to identify and fix the issue.

 Remember to check the basics such as battery placement, dirty contacts, blown fuse, and the presence of voltage before assuming the thermostat is faulty.

 If all else fails, don’t hesitate to seek support or consult a licensed professional. In the end, a little patience and effort can go a long way in ensuring that your thermostat is up and running smoothly once again.

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