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06 Apr 2022

Author: Jeff O'Hara

The thermostat that controls the activity of your HVAC system is essentially the “brain” of the operation. It constantly monitors the temperature in the home, instructing the furnace or air conditioner to power on or off as needed.

Thermostats have evolved quite a bit in just the last decade. Thanks to the integration of wi-fi technology and apps, coupled with HVAC systems that are getting more powerful and efficient every new model year, thermostats are more like control stations aboard a spaceship.

Without a properly functioning thermostat, it’s almost impossible to keep your home comfortable. When your thermostat is nearing the end of its useful life, it is likely to exhibit some symptoms that might indicate that it’s time to replace it.

Reasons Why Your Thermostat Isn’t Working

1. Old Wiring

How old is your home? It’s a relevant question to this topic, I promise.

However old your house is, that’s probably how old the electrical wiring leading to your thermostat is. No one ever woke up in the morning and thought, “today, I’m going to run a new power line from the circuit breaker panel to the thermostat!” And it’s because of that kind of laziness you’re having an issue with your thermostat!

Electrical wiring gets brittle as it gets older, which is caused by the copper conductor suffering from work hardening, a stiffness that occurs at any point where the wire is bent. Bending the wire –even just the tiny amount required to install it—creates small cracks that allow moisture and chemicals from the outer jacket to leech into the copper. When the gaps in the copper core are large enough, the wire breaks and the electrical signal can no longer reach the thermostat.

Symptoms that can be caused by older, brittle wiring can include thermostat displays that flash on and off. Turning on or off at unprogrammed or otherwise inappropriate times, or just not functioning at all can also be a warning that it’s time to look into the thermostat wiring.

2. Dead Batteries

Thermostats that can be programmed to run on a schedule require the installation of a battery to preserve those settings in the event of a brief power failure. When the power is restored –even if you’re not at home—your thermostat can tell your HVAC system to resume heating or cool your home without reprogramming. Most modern thermostats require AA or AAA-sized batteries, while some use flat, disc-style watch batteries. It would be best to replace the batteries in your thermostat at least once every year as part of your regular annual HVAC maintenance service.

Symptoms that can be caused by dead batteries would include a visual “low battery” indicator on the screen, along with losing all programmed memory whenever the AC power is temporarily lost.

3. Improper Programming/Operator Error

Losing control of your HVAC system’s thermostat can leave us questioning our sanity. We know we set the temperature to 70° just a few minutes ago, it’s hot outside, and the heat just came on! What is happening here?

Programmable thermostats –the old-school kind, not the wi-fi enabled variety—can inadvertently get switched into “auto” mode. While running a preset heating and cooling program is a great way to save money on energy costs, most homeowners never get around to programming their thermostats. When an un-programmed thermostat gets put into “auto” mode, the HVAC system is continuously “waiting for instructions.”

Symptoms that can be caused by improper programming are being locked out from making changes to temperature or heating/cooling modes.

4. Unit Is Locked Out

Every thermostat can be electronically “locked” to keep changes from being made to the temperature or runtime settings. As we learned above, having your thermostat set to run on a preset program will prevent you from making changes to when the unit start and stops. During programmed operation, it is possible to change the set temperature for the duration of that “on” cycle. That temporary setting is lost once the system powers off, reverting to the previously programmed set temperature.

Symptoms that can be caused by the unit being locked out is the inability to make any changes to temperature or heating/cooling modes from the thermostat panel.

5. Your Thermostat is Filthy!

Your thermostat is exposed to everything that gets carried around along with the air circulating through your home. Dust, dirt, pet and human dander, pollen, bugs, moisture, cooking grease, oils transferred from our skin, all sorts of gross stuff can collect on the surface of the thermostat, underneath buttons, and inside switches and sensors.

At a minimum, grab a damp rag and wipe down the outside of the unit every couple of weeks. If you’re the handy, do-it-yourself type of homeowner, take the thermostat off the wall and give it a thorough cleaning once or twice a year.

Symptoms that a dirty thermostat can cause include poor switch contacts due to dirt build-up and incorrect temperature readings thanks to dirt on the sensors.

What Can I Do Before I Call Nick’s Air Conditioning?

During an emergency service call, it’s always helpful to have as much information as possible before our arrival. If your thermostat, furnace, or air conditioner fails to operate, check to ensure that any circuit breakers associated with the HVAC system are turned on. Please make a list of the symptoms your thermostat may be experiencing and let your Nick’s licensed and experienced HVAC technician know about them.

Call Nick’s Air Conditioning today to arrange an appointment for your home’s thermostat or other air conditioning or heating issues.

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