Why does my thermostat reset?

Author: Peggie Predovic  |  Last update: Sunday, September 28, 2025

One of the most common reasons for a thermostat to reset itself is old batteries. If you haven't changed them recently, replacing them with new batteries is a good first step.

Why does my thermostat keep resetting itself?

Solution: Switch out your batteries. It can be as simple as switching out the batteries on your thermostat device. This could also be the reason your screen can go blank sometimes. Thankfully, most thermostats should tell you when the time comes to replace them.

How do I stop my thermostat from changing temperature?

If you have a programmable thermostat, you need to look for the 'hold' button. Manually turn the temperature up, or down to the desired setting, then press the 'Hold' button once. The word 'hold', or 'permanent hold', or something similar should appear on the digital thermostat.

How do you know if a thermostat is going bad?

A bad thermostat can be detected when your AC or furnace is not turning on, your HVAC systems are not turning off, the thermostat not responding, your HVAC system is short-cycling, the room temperature not matching the temperature displayed on the thermostat, and the programmed setting resetting themselves.

Why is my thermostat not staying at the temperature I set?

Some of the most common thermostat issues include:

The thermostat is broken, not properly level, or dusty. The thermostat needs to be recalibrated. There is loose wiring causing a thermostat issue.

How to Reset an AC Thermostat

How do I get my thermostat to hold the temperature?

This is where the “Hold” button on your thermostat comes into play. By pressing “Hold”, your thermostat will lock in the temperature it's currently at until you change it again. When you are ready for your normal schedule to resume, simply press the “Run” button and return to your typical programming.

Why is my AC thermostat set at 74 but reads 78?

If the temperature is set to 74°F but the thermometer shows 78°F, you will have to recalibrate the thermostat to account for this 4-degree deviation. Even with older AC units or furnaces, you might have to recalibrate your thermostat from time to time.

How can I tell if I need to replace my thermostat?

Signs You Need a New Thermostat
  1. Heating or cooling system will not turn off or on.
  2. The temperature reading is incorrect.
  3. Recent spike in your energy bill.
  4. Frequent temperature fluctuations.
  5. Thermostat is 10 years old or older.

What is the lifespan of a thermostat?

The Lifespan of a Thermostat

On average, most thermostats last about 10 years, depending on the model, usage, and proper maintenance. However, many people decide to replace their unit sooner to take advantage of new energy-saving technologies.

How do I test my thermostat?

Methods for Testing Your Thermostat
  1. Just Turn it On and Let it Work. One way to test your thermostat is to simply turn it on and see if it cools the room down. ...
  2. Get an Indoor Thermometer. Another way to test your thermostat is to use a thermometer. ...
  3. Use a Multimeter. ...
  4. What to Do if You Notice an Issue.

Why does my thermostat keep going down to 62?

Thermostat battles—If your thermostat keeps dropping to 62 degrees after you've bumped it up to a cozy 70, it might not be the thermostat. With app-based controls, other family members may adjust or turn off your temporary hold. Find out who else can access the thermostat app, or consider changing the account password.

Why is my house colder than the thermostat setting?

Your house and attic insulation can wear down over time. Your house also may have hidden attics that aren't properly insulated or uninsulated garage walls that are attached to your home, and this can cause problems with heat escape, unwanted airflow, and drafts. Your ductwork has problems.

Can thermostats change on their own?

The only reason it may change by itself is you have a programmable thermostat that has a schedule running on it. Either that or someone is moving it without your permission. Assuming it's the first, try locating the “hold” button.

How do you know if you need to reset your thermostat?

Certain situations may require you to reset your thermostat. For instance, if it's cold outside, and you're cranking up the temperature for your furnace but the house still doesn't feel like it's warming up, you may need to reset your thermostat.

How do you fix a malfunctioning thermostat?

How to Troubleshoot and Fix a Broken Thermostat
  1. Step 1: Verify Temperature Settings. ...
  2. Step 2: Inspect the Power Supply. ...
  3. Step 3: Reset the System. ...
  4. Step 4: Clean the Thermostat. ...
  5. Step 5: Calibrate the Thermostat. ...
  6. Step 6: Test the HVAC System. ...
  7. Step 7: Upgrade to a Smart Thermostat.

Can a thermostat lose calibration?

Once you set your thermostat (the main interface between you and your HVAC system), you likely assume it's guiding your heating system to warm your home to the set temperature. It may not be. Thermostats can lose calibration over time from being accidentally bumped or from dirt accumulating.

How can you tell if your thermostat is bad?

7 Ways to Tell Your Thermostat Is Broken
  1. The Thermostat Has No Power. ...
  2. The AC or Furnace Won't Turn On. ...
  3. The Heater or AC Won't Turn Off. ...
  4. The Thermostat Reading Doesn't Match the Room Temperature. ...
  5. The Thermostat Doesn't Respond. ...
  6. The HVAC System Is Short Cycling. ...
  7. The Thermostat Forgets Programmed Settings.

Do I need an electrician to replace a thermostat?

Yes, many smart thermostats are designed for DIY installation, and manufacturers typically provide step-by-step guides and videos. However, if your HVAC system is older or lacks proper wiring (like a C-wire), the installation might become more complex, and you may need professional help.

What does short cycling mean?

In the heating, ventilation, and air conditioning (HVAC) business, short cycling is a phrase used to describe when a heater or air conditioner cycles on and off too frequently. It signifies a problem in your heating system's proper functioning and efficiency, in which it is not completing its heating processes.

Can I replace my thermostat myself?

In most cases, installing a new thermostat is a relatively simple do-it-yourself project that can result in improved comfort and convenience and one that can help you save energy.

What are the symptoms of a thermostat not opening?

High temperature readings

The main symptoms of a failing thermostat are related to engine overheating. It can be easily noticed because the temperature gauge in the vehicle will probably read unusually high. This can be caused by the valves being stuck in a closed position.

Why does my thermostat time keep changing?

Weak or Old Batteries

One of the most common reasons for a thermostat to reset itself is old batteries. If you haven't changed them recently, replacing them with new batteries is a good first step. Weak batteries can't maintain the necessary power to keep your thermostat running properly, leading to resetting issues.

How cool should my house be if it's 100 outside?

For many of us, 70 degrees is the ideal indoor temperature, but when it is close to 100 degrees outside, your AC unit will be working quite hard to meet these expectations. Consider setting your thermostat at 75 degrees to 80 degrees in your home if the outside temperature is approaching triple digits.

Why won't my thermostat stay where I set it?

Clean the Thermostat

Sometimes, when the room temperature doesn't match the thermostat setting, the problem could be dirt buildup on its interior parts. A dirt coating around the inner components may create excess heat and cause the thermostat to give the wrong readings.

Why is my house hotter than the thermostat setting?

Another problem that can cause your house to be hotter than what you've set the thermostat to is if your home's HVAC system isn't sized properly. An HVAC system that's too large for your house will cool your home unevenly. It will only cool some rooms off and then shut off versus cooling down the entire house.

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