Your AC system is complex and interconnected. The AC system won’t function at peak efficiency if one of its components fails. If the thermostat stops working, the system can’t work at its peak efficiency. The thermostat is the box on the wall that controls the AC. You can’t switch your AC on/off or adjust the temperature if there is no power supply.


Here are some things to do when your thermostat goes offline. It’s essential to ensure that your thermostat is on, which is particularly important for older thermostats. Digital thermostats that are still receiving power will show some information even if they are turned off. If the thermostat’s display screen goes blank and is digital, it has lost its ability.

An older thermostat may need to be replaced if it is still working. It would help if you replaced the batteries about once per year to keep your thermostat working correctly. Try replacing the thermostat’s batteries if it stops working.


If the thermostat appears to be on and has batteries, the circuit breaker is next to check. As with all electrical appliances in your house, the thermostat is connected directly to the circuit breaker. If your thermostat’s circuit supplies too much electricity, it will turn off automatically, and the course will turn off.

Inspecting your circuit breaker to see if the switch is turned off and then flipping it on again is easy. This will sometimes fix the problem, and sometimes the button will go back. If you notice this happening in your home, you might need to upgrade or diagnose another problem.


If none of the above steps resolves the problem, another issue may arise. Sometimes, the thermostat may lose power due to a pain in the safety switch. The majority of AC safety switches can be found near the drain pan. The controller can trip if there is excessive moisture, and this will cause the thermostat to stop receiving power. If this happens, it is essential to have your AC checked by a cooling and heating specialist.


Your thermostat can go blank if there is a problem with the wiring or transformer. A broken thermostat could also cause your thermostat to go blank and require replacement. Every thermostat reaches the end of its lifespan, and it is a good idea if your thermostat is older to get a newer one. You can set your thermostat to adjust the AC temperature to suit your daily schedule and comfort level.

Smart thermostats are an updated version of programmable temperature controllers. These can be controlled remotely via your computer or phone. This allows you to set your AC to run in advance according to your daily schedule and make adjustments as necessary if an unexpected situation arises.

You can even set reminders on your smart thermostat to remind you to change your AC filters regularly. One of the most simple and essential ways to prolong the life of your AC is to replace dirty filters. Many homeowners find reminders from their smart thermostats extremely useful.

If you cannot identify the cause of your thermostat not working, it’s time for an HVAC specialist. To diagnose the problem, a professional can inspect your AC unit, and they will find the solution to the problem and help prevent it from happening again. They can also schedule regular maintenance checks to prolong the AC’s lifespan and keep it running efficiently. This will save you money and keep you and your family comfortable through all seasons.

Thermostat Testing if Wire is Getting Power

Sometimes it isn’t easy to know if the thermostat is getting power. The thermostat and other AC parts can sometimes become loose or corroded, and rodents may chew these wires. Problems with wiring can lead to problems in the thermostat’s power flow. To check if your thermostat is receiving power, it is easy to conduct a thermostat test.


It doesn’t take special tools or knowledge to do the most straightforward wiring test. Change the thermostat’s fan setting from Auto to ON. Listen carefully to hear if the blower is roaring. If you hear the blower start-up, power reaches your thermostat.

The AC can be turned on, and the mode selected for the season (Cool for summer, Heat for winter). Next, adjust the temperature setting to either decrease (in summer) or increase (in winter). It would help if you changed the thermostat to be lower or higher depending on the temperature in the room. If your thermostat wires are conducting electricity as they should, you should hear normal sounds when your AC starts.


These are just a few tests you can do to check the wires. To do this, remove the thermostat cover to reveal the wires. If you can’t see the wiring after you remove it, you might need to use your screwdriver to take off the mounting plate. Once you can see the wires, you can examine several different-coloured wires connected to terminals marked by letters.

These wires have a relatively low voltage. You should turn off the circuit breaker power before touching or disconnecting the cables. You’ll need to be attentive to the two main wires once you have shut off the power. One is the red wire that connects to the R-terminal, and the other wire is the green one connected to the R terminal. This relates to AC’s blower.

After the power is turned off, disconnect the red and the green wires and twist their ends. Next, turn on the power. It will if the AC blower turns on when these wires conduct control correctly.

A multimeter can be used to verify that wires are operating correctly. You don’t have to shut off power or disconnect thermostat wires from the terminals. Set your multimeter for 24 volts AC. Then, touch the R terminal with one of the probes. Touch the other probe to the G, W, or Y terminals.

If power flows to the thermostat, the multimeter should register readings of between 22 and 26 V. A reading of 0 V indicates that energy is not flowing through the wires.

Most homeowners don’t have any multimeter tools. You can avoid DIY projects that expose wiring or pose a risk of electric shock. An expert can quickly test the thermostat wiring and determine its functioning correctly. To get your system up and running again, they will make any AC repairs.

How To Change a Thermostat

An AC professional can replace your thermostat if your thermostat is damaged. However, some people like the challenge of changing a thermostat, and it isn’t tricky to do it yourself. Ensure the new thermostat is compatible with all your heating and cooling systems.

Here are step-by-step for replacing an outdated or broken thermostat.

  • To avoid electric shock, you must first turn off the thermostat.
  • Next, take out the old thermostat from the wall plate. The wires will now be exposed. You can use a multimeter to check the voltage or a circuit tester.
  • Look at the connections between the wires. Each wire should be different in colour and connect to a terminal marked with a different alphabet. To make it easier to find the wiring later, take a picture. Tape should be used to identify each wire by the letter it connects with. (Pre-printed labels may be included with the replacement thermostat you purchased.
  • Once each wire is labelled, it’s time for you to disconnect them from their terminals and use a screwdriver or pliers to remove the old wall plates.
  • The old anchors can be reused if your replacement thermostat’s mounting holes match your existing wall anchors. The new unit may have slightly different spacing holes. In this case, it will be necessary to drill new holes at the correct spots and install new anchors.
  • Some people prefer to remove wall anchors from the walls and then patch the holes. The old holes can be left as-is if the new plate can be attached flush to the wall.
  • The next step is to install your wall plate. Once the plate is installed, feed the wires through it. When mounting the plate, make sure it is straight.
  • To ensure that each wire is correctly inserted into the terminals on your new thermostat, make sure you read the instructions. Finally, screw the terminal screws in place. If your new unit needs a C-wire, you will probably need a professional to complete the job.
  • Next, attach the batteries to the thermostat and mount them on the wall plate.

Once the thermostat has been installed, you need to turn the power off to verify that it still works. It is a good idea to call an AC professional for any problems during installation. A licensed specialist can take care of any AC repair task, large or small, and maintain your heating/cooling system in good condition. This will reduce your monthly electricity bill and extend the lifespan of your AC.

ABC Can Help You With Your Thermostat Problems

Thermostats can be complicated, and problems can occur for many reasons. ABC Home & Commercial Services will help you to diagnose and fix these problems. Our experts will quickly diagnose and fix the HVAC problem. We also offer preventative AC Maintenance to identify potential issues before they become serious.


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