Alpharetta’s premier A/C repair specialists at Gagne Heating & Air explain how to fix a broken digital thermostat

thermostat not working

The central command center for your indoor air temperature – your thermostat – is a small piece of technology that can run into a surprising amount of potential problems. If your thermostat isn’t showing signs of life, if it’s not accurately maintaining your desired temperature, or if it is just doing weird stuff like turning itself on and off, then you’re facing one of the many possible thermostat problems that plague homeowners and businesses.

Here, our expert Atlanta heating and cooling technicians will walk you through some possible problems that might be affecting your thermostat’s functioning, along with some possible solutions.

Is the thermostat turned on?

It sounds like a silly question, but the number of people who, frustrated with the thermostat’s failings, realize that it was actually turned off may surprise you. Make sure your thermostat is on and that, in the case of heating, the temperature set higher than the room temperature the thermostat is currently reading. In the case of cooling, make sure that the thermostat reads lower than the current room temperature.

Is the thermostat clean?

If your thermostat is acting screwy, it might be because it’s dirty. Buildup of dirt, dust and nicotine can all coat the inside, which may interfere with electrical and mechanical components within the thermostat. If you open the thermostat cover and notice dust, use a compressed can of air to clean the components.

Is there power?

If your thermostat isn’t showing the display, it may not be getting any power. There are three places you should check to ensure your thermostat is properly receiving power:

  1. Check your circuit breaker. Your thermostat is wired into the electrical system. If the circuit the thermostat is on trips, then there will be no power to the thermostat. Go to your breaker box, locate the breaker that the thermostat is on, and make sure the switch is flipped to the on position.
  2. Check the thermostat’s fuse. Some thermostats have a fuse located inside the device as additional protection from power surges. These fuses may occasionally blow or go bad. To check your thermostat’s fuse, take off the cover. The fuse will look like a clear canister with metal ends. Inside the fuse will be a filament that runs the length of the canister. If this filament is broken (just like the filament in an incandescent light bulb) then the fuse will need to be replaced.
  3. Check the batteries. Most electronic thermostats run their display and controls on battery power. To find the batteries in your thermostat, take off its cover. The back panel of the cover often tell you where the batteries are located. If you can’t find them, consult your thermostat’s manual.

Is your thermostat in the right location?

If your thermostat is “working” but you’re continually unsatisfied with its results, then it might be poorly placed in your home. Thermostats placed near drafty windows, doorways or stairwells may not read the average temperature of the house correctly. Likewise, having a thermostat located too close to sunny spots or your kitchen can also alter readings. Moving a thermostat to a different location will require a professional.

How do you test a thermostat?

Since digital thermostats are electrical, we highly recommend contacting a professional repairman to test your thermostat. However, many homeowners like to at least try to fix such problems on their own first. If you want to determine if your thermostat is sending a signal, here are some DIY instructions on how to safely do so:

  1. Turn of the power. This first step is VERY important. Make sure the electricity to your thermostat is switched off by turning off the correct breaker. Failing to do so could lead to accidental electrocution.
  2. Remove the thermostat cover. Once the power is turned off, take off the front cover to expose the wiring.
  3. Take a picture. We recommend taking a photo with your phone or a camera of how the wiring in the thermostat looks before messing with anything, that way you know how to put it back when finished.
  4. Unscrew the wires. Loosen the screws labeled “R” (or “Rh”) and “W”, then remove the wires from beneath.
  5. Twist the ends. Twist the ends of these two wires together and then go turn on the thermostat breaker again. If the AC or furnace comes to life, it means the thermostat is not sending a signal and will need to be replaced. If the system doesn’t turn on, then the air conditioner or heater is likely malfunctioning.
  6. Finish the job. Once you’ve determined whether the thermostat is sending a signal or not, switch off the breaker again, untwist the wires, screw them back into the board and put the cover back on.

“I’ve tried everything you’ve listed here with no luck!”

If none of the above steps help solve your thermostat woes, then it might very well be dead. Check your thermostat’s guidebook since some higher-end thermostats from brands like Honeywell, Goodman and Nest carry limited warranties. Otherwise, it’s probably time to buy a new one.

If you’re needing to replace your old thermostat with a new one, we recommend going with a programmable thermostat. Check out this Home Depot instructional video on how to replace an old thermostat:

If you’re not sure what’s going on with your thermostat, or if your problem even is your thermostat, be sure to call the experienced metro-Atlanta A/C repair technicians at Gagne Heating and Air. Besides offering installation and service, we offer emergency repairs to homes and businesses in Alpharetta, Chamblee, Doraville, Sandy Springs, Marietta, Roswell, Duluth, Buckhead, Johns Creek and other communities in the Atlanta region.

Contact our experts today or continue reading on our Knowledge Center and blog to learn more about your heating and cooling systems.

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