Why is My Thermostat Not Working? How to Fix [With Pictures]

Do you ever get that feeling that your thermostat is out to get you? No matter what you do, it never seems to work? When you find your thermostat not working, you probably feel lost on what to do. You're most definitely not alone. In fact, a lot of people have thermostat issues - and it can be extremely frustrating. But don't worry, we're here to help. Here are some tips on how to troubleshoot and fix this problem so that you can be more comfortable in your own home!

How To Troubleshoot Thermostat Not Working

If you're like most homeowners, your thermostat is one of the most important pieces of equipment in your home. It's responsible for regulating the temperature and keeping you comfortable all year round. But what do you do when your thermostat isn't working? 

Step 1: Change Batteries

Changing out the batteries in your thermostat is one of those little things that can make or break cooling down at home. If you notice a thermostat error, don't hesitate to get new batteries installed! Replacing the batteries is a simple task and only takes a few minutes. To check the batteries in the thermostat, you will need to remove it from the wall. Once you have removed the thermostat from the wall, you will need to use a screwdriver to remove the battery cover. 

Step 2: Check Circuit Breaker

If your thermostat is not working, you may want to check the circuit breaker. The circuit breaker is responsible for supplying power to the thermostat. If the circuit breaker trips, the thermostat will not function properly. To check the circuit breaker, you will need to locate the breaker box in your home and identify the breaker specific for your thermostat. Once you have identified the breaker, you will need to switch it off and then back on again. 

Step 3: Check Thermostat Programming

If the thermostat is not working, it may be due to a programming error. In order for the thermostat to operate as it should, it must be programmed correctly. Thermostats can be a bit tricky to program, especially if you're not sure which mode is suitable for your home. To make sure the thermostat is programmed correctly, you must refer to the owner's manual. The owner's manual will provide you with information for navigating the controls on the thermostat to set it according to your needs. You can learn more about how to recalibrate your thermostat here.


Common programming discrepancies include running the thermostat for a heat pump system instead of a furnace and vice versa. Many do not realize that thermostats can be compatible with multiple types of equipment. If the thermostat for your furnace is functioning the way it needs to work for a heat pump, you will have your furnace and AC competing against each other. As a result, your utility bills skyrocket.


Some thermostats run based on a programmed schedule. This means that the set temperature varies depending on the time of day. So, for example, the thermostat may run the set temperature to be 68 degrees from 7 am-7 pm, and after 7 pm it raises the set temperature to 70 degrees. If it seems like your thermostat has a mind of its own, it may be programmed to run on a pre-set schedule. 


A Smart Thermostat can automatically adjust the set temperature based on how frequently the homeowner is home or away. This feature is meant to optimize efficiency, but the homeowner can disable it if they so choose. 
And lastly, verify the thermostat is set to Cooling mode if you want air conditioning and set to Heating mode if you desire hot air.
Each thermostat configuration is different, but the owner's manual guides you through the programmable settings. If you are having trouble programming your thermostat, just give us a call.

Step 4: Ensure The Furnace Switch Is Providing Power To The HVAC System

Sometimes your thermostat may not be working due to a problem with your air conditioner or heating system and not as a result of a faulty thermostat.

If the thermostat is not working, it may be due to a problem with the furnace. The furnace switch must be on for the thermostat to work. To make sure the furnace switch is on, you must locate the furnace. There will be a switch on the wall close by that looks just like a light switch. This controls the power to the furnace. If the furnace switch is in a downward/off position, then turn it up/on.

Step 5: Facilitate Air Flow

If your thermostat is not working, you may want to check the airflow. Airflow is a significant factor in how your heating and cooling system performs. The airflow is responsible for supplying cool air to the rooms in your home. If the airflow is blocked, your HVAC system will struggle to satisfy the thermostat, and the thermostat will not function properly. Therefore, check if there are any closed or blocked vents. Next, move all obstructions to allow for a steady stream of cool air in and hot air out (or vice versa in the winter). 

If your thermostat is not working, you may want to check the filters. The filters are responsible for trapping dirt and dust particles. If the filters are not working, the thermostat will not be able to function correctly. When the air filters are dirty and clogged, air will struggle to pass through them. This reduces cooling and heating efficiency as well as strains the HVAC components. If the HVAC system struggles to keep up with the thermostat set temperature, it can explain it not working.

Learn how to change your air filters here! However, if you need help changing your filters or if the thermostat still isn't working, you may need to call a professional for help.

Why Your Thermostat Is Not Working:

A Bad Thermostat Control Board

If your thermostat is not working, it could be because of an issue with its control board, which communicates with the HVAC system to ensure everything runs smoothly and efficiently. The thermostat control board sends signals to turn the cooling and heating functions on and off. If the thermostat control board is faulty, you will experience your thermostat not working

Dead Batteries

One of the most common reasons why thermostats are not working is because the batteries are dead. If the batteries in the thermostat are dead, the thermostat will not be functional. You will then need to replace the batteries in the thermostat. If the thermostat is still not working, you may need to call a professional for help.

Poor Wiring

The malfunctioning thermostat may be due to faulty thermostat wiring. If the thermostat wiring is loose, dirty, disconnected, or bad, the thermostat fails to function properly. 

Thermostat Not Programmed Correctly

The thermostat is an essential device in your home. If a thermostat is not programmed correctly, you'll experience thermostat problems. The thermostat could be working against the homeowner due to faulty programming. You may have the thermostat programmed for the wrong type of equipment, running a pre-selected temperature schedule, set for the wrong mode, or bad connections. If any of these things happen - don't worry because we can help fix everything from here by just reprogramming them back up again, so they work as expected every time now without issue.

Faulty High Voltage Wire

An issue with the high voltage wire may be the cause of a malfunctioning thermostat. If there is a problem with the high voltage wire, the thermostat will not be able to signal the HVAC system properly. A high-voltage wire that is damaged, loose, or disconnected causes thermostat problems.

Bad Thermostat

If your thermostat is not working, one of the possible reasons may be a bad thermostat. Just like all mechanical devices, a faulty thermostat is a fluke that sometimes just happens. A bad thermostat can cause several problems, including not turning on the cooling or heating functions, not reaching the desired temperature, showing an error message, or displaying incorrect temperature readings.

No power: Furnace Switch Off or Circuit Breaker Tripped

The HVAC system needs power to operate, and if the HVAC system cannot start, you will be stuck with a thermostat not working. If your thermostat is not working, ensure your furnace switch is on, and your HVAC circuit breaker is correctly set.

Blown Fuse

If your thermostat is not working, one of the possible reasons may be a blown fuse. The thermostat cannot communicate when a sudden electrical incident such as a blown fuse occurs.

Problem with AC or Furnace

Often, your thermostat is not working due to an issue with the air conditioner or furnace. If the thermostat can never satisfy the desired temperature, the problem may originate from your heating or cooling system. In particular, you may find that your AC is not turning on, blowing hot air, leaking water, or freezing. When the AC or furnace is not working, the thermostat will appear not to keep up. Some common problems with the AC or furnace that can create a thermostat problem include a bad blower motor, low refrigerant, or leaky ductwork. With your furnace, you may find it blowing cold air, leaking, or at the very worst not turning on at all. There are multiple factors at play when you have a thermostat issue. Only an HVAC professional can diagnose the root of the problem and offer a technical solution.

Poor Airflow

If the thermostat is not working, one of the possible reasons may be a problem with the airflow. When air is blocked from circulating through the heating or cooling process, the HVAC system can not keep up, and thus the thermostat will not satisfy the desired set temperature. Additionally, when there is an airflow problem, it can cause the furnace or AC to overheat or freeze. A dirty filter, blocked or closed vents, and a dirty HVAC system can inhibit airflow, directly showing up on the thermostat.

How To Keep Your Thermostat Working All Year Long

Your thermostat and HVAC system will function at its best when you need it most if it is maintained in top condition. Regular maintenance will ensure your entire system is in good working order for when you rely on your HVAC system; regular maintenance helps prevent heating and cooling problems. During a tune-up, an HVAC specialist will evaluate all requirements for proper airflow, asses all wire connections, and assess each mechanical component. Unfortunately, many people neglect to maintain their HVAC systems. This can lead them into trouble when they need it most! Luckily for you though, there is now an easy solution- regular maintenance with the specialists will make sure that your system stays in top condition so everything runs smoothly and prevents any problems before they happen. Because of routine maintenance, you won't have to worry about a faulty thermostat ruining your day!

Time To Get Comfortable

So, your thermostat is on the fritz and you're not sure what to do? First of all, don't panic! We know that having no heating or air conditioning in the middle of summer or winter can be a huge headache. But before you start calling around for thermostat repair or a new thermostat installation, there are a few things you can try. If your thermostat is not working, change the batteries, make sure it is turned on, the thermostat is set to the correct mode, check the power supply and airflow. 


If your thermostat is still not working, the best thing to do is call an HVAC professional! They will be able to help you diagnose and repair the issue. Not only will this save you money in the long run, but it will also ensure that your home stays comfortable all season long. Have a great day!

- Let SuperTech take care of it for you. We'll get your home comfortable again in no time. Schedule here now!


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