AC Maintenance: Thermostat

Video Transcript

Thermostat Maintenance

Dean:         The one thing that homeowners really know better than anything is the thermostat. Thermostat basically just controls the unit. This is a duh, no brainer.

George:      When you check the thermostat, you’re gonna check the connections, the wire connections into the thermostat. Make sure they’re still good and tight. And you’ll check the display, make sure everything’s lit and working properly on the display. You don’t have no numbers that are half a number showing or there’s like glitches where it’s constantly flickering or anything like that.

Dean:          What could cause a glitch?

George:      It’s like a computer. It’s a circuit board, pretty much. Make sure you got adequate voltage going to the thermostat.

Dean:         So the voltage could mess up your thermostat.

George:      It can.

Dean:         So instead of buying a $400 thermostat, it could’ve been a $49 transformer.

Battery Backup

George:      Right. A lot of thermostats have batteries as backup to keep the memory and everything, if the power goes out. Check the battery connections and make sure they’re not corroded.

Dean:          A lot of things that could happen that you need to check, guys.

George:      The thermostat, it comes from the factory with a default program in it.

Dean:          So if the power goes out because we’ve had an ice storm and the power’s out for two hours and your thermostat goes back into default, does it reset itself?

George:      Well, when it comes back up, it may default back to factory settings, so you might have to go back and change it back to where you want.

Dean:         So if you’ve had it programmed for your desired comfort level, the power goes out, you’ve got to do it all over again, reprogram it?

George:     You may have to. If you don’t have no battery backup or something, you may have to go back in and set it all back.

Dean:         If you’re like me, I don’t even know how to program my thermostat. I’d go crazy trying to figure that thing out.

George:     Sometimes, the batteries, they don’t see the battery’s gone dead, so when it goes out, it loses it.

Dean:         There you go.


A thermostat (aka “T-stat”, if you’re into the whole brevity thing) senses the temperature in your home, then controls the air conditioning system to cool it down to your desired temperature. These are the steps a service tech uses to test your thermostat during a maintenance check.

How to Check the Thermostat

1. Ensure Proper Installation

digital thermostat

We’ll check to make sure your thermostat is installed properly and away from sources of heat, like light bulbs, sunlight, or heat-producing appliances. Extra heat can throw off the temperature sensor in the thermometer.

2. Check the Wire Connections

a gif of checking the thermostats wiring

Make sure they’re still good and secure.

3. Measure Voltage

measuring thermostat voltage

The thermostat is like a computer, with a circuit board that can be damaged by improper voltage. So checking the voltage can be the difference between paying $400+ for a new thermostat, or just $49 for a transformer. That’s another way we save you money!

4. Check the Digital Display

thermostat digital display

We’ll check the display for signs of malfunctioning, making sure everything’s lit and working properly. You don’t want glitches, like constant flickering, or numbers not showing up.

5. Check the Battery

digital thermostat loading screen

Many modern electronic thermostats have a battery backup to keep the memory in case the power goes out. If the thermostat completely loses power, it may lose your comfort level preferences and revert back to factory settings once the power comes back. We’ll check the battery to make sure it’s not dead and that the connections aren’t corroded.

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