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My Thermostat Is Not Working: What’s Going On?

a thermostat not reaching the set temperature

Imagine that your air conditioning unit stops working just after your family has arrived for a visit in the middle of summer. Or, that your heater breaks down right at the coldest point of winter. Few things are more frustrating than you and your family having to deal with these extreme temperatures. Plus, it is stressful not knowing what might be the problem or how to fix it.

If you are noticing heating or cooling issues, this might mean that your thermostat is not working. One sign that might point to an issue with your thermostat is if your air conditioning unit is not reaching the set temperature. Similarly, if the unit keeps shutting off early or it is running all the time, then your thermostat might be the problem. Another common sign is if the display on the thermostat is blank.

Sometimes, homeowners can fix these kinds of problems by doing some simple troubleshooting on their own. Unfortunately, trying a DIY approach often takes a lot of time due to trial and error because there are a number of different things that could be causing your system’s issues. When you and your family are dealing with a broken air conditioning and heating system, you likely do not want to waste any time.

That is why it is wise to reach out to a licensed specialist. A professional can diagnose the root cause of the problem and take care of everything for you. Professionals have the training and tools needed to figure out if your thermostat isn’t working or if something else might be the problem. They also have the knowledge and skills needed to fix these kinds of problems, so you and your family can be comfortable again.

However, if you would like to try to diagnose the issue on your own, there are a few things you can check. Some of the most common reasons why your thermostat might not be working include the following.

Wires or Connections Are Dirty, Dusty, Corroded or Loose

Check the wiring in the thermostat. Contact a professional to tighten any loose wires and replace those that look corroded. If the inside components of the thermostat look dusty or dirty, you can use a compressed air sprayer or gentle brush to carefully clean grime off the wires. Remember that with electrical wiring, it’s necessary to shut off the power supply first to help reduce your risk of electrocution. Then, you can start working on your thermostat.

There Is an Internal Mechanical Issue or the Thermostat Is Bad

There could also be a calibration or mechanical issue with an internal part, such as the heat anticipator. To fix this kind of problem, consult the instructions in your owner’s manual. It should explain how to check and troubleshoot parts of your model of thermostat.

Or better yet, you can contact an air conditioning and heating specialist. These experts can advise you on whether a particular part needs replacing or if you might need a new thermostat altogether.

The Thermostat Has No Power

It might be possible that your thermostat is just set to the “off” position, which is easy to fix by switching it back on. If this does not work, you can also try resetting the thermostat. Another possibility is that something might be wrong with the power supply. There could be an issue with the batteries inside the unit or with your house’s electrical system.

If you think this might be the issue, check the fuses in your home’s electrical panel, and have any blown fuses replaced. If you find that a breaker has tripped, then flip the circuit breaker for the thermostat back to the on position. Lastly, if your thermostat has batteries inside it, then you can replace the batteries to see if this fixes the problem.

The Thermostat Might Be On the Wrong Setting

Your thermostat might not seem like it is working correctly if it is on the wrong setting. For example, if your AC is blowing warm air, make sure your thermostat it is set to “cool” instead of “heat”. Problems can also occur if the fan on the thermostat is set to “on” instead of “auto”. This is because this signals the system to run constantly, even if your house has already reached the correct temperature.

The Thermostat Is Not Level or It Is Not in a Good Place in the House

If your thermostat was installed crooked or in a bad spot, this can cause it to have trouble sensing the true temperature of the house. For example, if your thermostat is in the kitchen, this can cause it to think the whole house is warm. In reality, it might be just the room where the thermostat is located that is hot, while the rest of the house might be freezing cold.

a white and light gray living room

Thermostat Not Reaching Set Temperature

One common thermostat problem you might face is when your home won’t reach the temperature that you set it at. This issue can happen for a number of reasons. Some of the most common things that can cause this problem include the following.

The Thermostat Needs To Be Recalibrated

The calibration on your thermostat can get messed up if the thermostat is new or if you have had a power outage recently. If this is the issue, then recalibrating the thermostat should fix the problem. However, if this does not correct the issue or if you find yourself having to recalibrate the thermostat several times each year, then your thermostat might have gone bad or have another problem.

A Dirty, Broken or Unlevel Thermostat

When a thermostat is first installed, it should be level and should be placed flush against the wall. Otherwise, this can affect the thermostat’s ability to read the temperature of the room. Similarly, the internal parts of your thermostat can break down, loosen or gather dust over time. This can also keep the unit from working like it should.

The Ducts, Vents or Air Filters in Your Home Are Dirty

If your air filter is clogged or the vents or ducts are dusty or dirty, this can block air from flowing through your HVAC system. This can keep the thermostat from reaching the set temperature. You can prevent this problem by signing up for regular AC maintenance.

The HVAC Unit Is Too Small

Each air conditioning and heating unit is typically made to heat or cool a certain size home. If your unit is too small, then it will have trouble getting the right temperature air to all areas of your house. This can particularly be an issue if you have expanded your house by doing something like adding an extra room. If this is the problem, you might consider buying a larger HVAC unit or adding an additional unit to your home.

The Thermostat Is Not in an Ideal Spot

The best spot for your thermostat is on an interior wall, away from windows, exterior doors, heaters and powerful lights. This will help ensure that the sensor on the thermostat can get a good reading on the true average temperature in your home.

Since so many different issues can prevent a thermostat from reaching the set temperature, the easiest way to fix this problem quickly and effectively is to contact a specialist. These professionals can not only provide you with a diagnosis of the heating or cooling problem, but they can also take care of everything needed to get your thermostat working.

an air conditioning vent

Can a Thermostat Go Bad?

With routine maintenance, home thermostats can typically last an average of 10 years. However, thermostats can sometimes last longer than the average lifespan or can stop working earlier. Some signs that your thermostat might need to be replaced include:

  • Your system has started short cycling or turning off before it has finished its cycle
  • The thermostat display is blank or the unit keeps shutting off, and checking the power supply does not fix it
  • Your energy bills are higher than normal and you can’t figure out why
  • The temperature reading on your thermostat is not correct
  • The system does not respond when you change the temperature setting

If you think your thermostat might be going bad, it is time to call an air conditioning and heating expert. A professional can figure out if your thermostat is the problem. They can also give you the information you need to decide whether to repair your HVAC unit or buy a new one. Professionals bring the experience, diagnostic tools and skills needed to get repairs done quickly and correctly.

ABC Can Diagnose and Fix Thermostat Problems

It can be uncomfortable and frustrating when your thermostat won’t work the way you need it to. Don’t waste time by attempting to fix these issues on your own. When it comes to heating or cooling problems, you can count on ABC Home & Commercial Services. Our licensed specialists will quickly get to the root cause of the problem and get to work on fixing it.

Tom Riggs

Tom Riggs is the Division Manager for Mechanical Services, overseeing sales and operations for HVAC, Plumbing, Electrical, Appliance Repair and Water Quality for all ABC Austin branches. He joined ABC in 2014. Before ABC, he was an HVAC Service Technician, HVAC Comfort Advisor/Sales and Operations Manager. Tom attended Universal Technical Institute. He's an avid outdoorsman and enjoys country living with his wife and two sons.

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