When your HVAC system isn’t keeping your home comfortable, it’s easy to assume the issue lies with your furnace or AC. But at Sub Zero Temp Control here in Vancouver, WA, we often get calls from homeowners asking, how do I know if my thermostat is bad? It’s a great question—and the answer isn’t always obvious. Your thermostat is the control hub for your entire system, so if it’s not working right, the rest of your equipment can struggle to keep up.
Below, we’ve outlined five clear signs that your thermostat might be the real issue.
1. How Do I Know If My Thermostat Is Bad? Watch for Temperature Swings
If your home feels comfortable in one room but uncomfortably hot or cold in another, the thermostat could be to blame. Uneven temperatures are one of the most common red flags we see here in Vancouver homes. It could be that the thermostat is reading the temperature incorrectly or sending mixed signals to your system.
We see this often in homes throughout the Vancouver area. In many cases, replacing the thermostat or simply relocating it to a better spot quickly resolves the issue and restores consistent comfort.
2. System Won’t Turn On or Off at the Right Times
Another telltale sign is when your heating or cooling system doesn’t respond. Maybe it runs constantly, or maybe it doesn’t start up at all—even when you change the temperature settings. This is often due to wiring issues or internal failures in the thermostat itself.
We’ve seen this happen in many homes throughout the Vancouver area. In many cases, the HVAC equipment is working fine, but the thermostat is breaking the connection.
3. How Do I Know If My Thermostat Is Bad? Check the Display
A blank or frozen screen is a classic red flag. Try changing the batteries and resetting the breaker. If that doesn’t work, your thermostat might be done for. This is especially common in older homes where thermostats have simply reached the end of their lifespan.
In many cases, replacing the thermostat restores full control and brings your HVAC system back to normal.
4. Your Energy Bills Are Higher Than Normal
You might not notice anything wrong with your HVAC system at first—but your utility bill might tell a different story. When a thermostat is sending inaccurate signals, it can cause your system to run longer than necessary. That means wasted energy and higher costs.
We’ve helped many homeowners lower their energy bills by recalibrating or replacing an outdated thermostat. It’s a simple upgrade that can lead to noticeable savings month after month.
5. The Room Temperature Doesn’t Match the Thermostat Setting
This one’s easy to test. Set your thermostat to 70 degrees, then place a thermometer nearby. If the actual temperature is far off, your thermostat could be miscalibrated or poorly placed—like near a heat vent or in direct sunlight.
We’ve corrected this issue in many homes by moving thermostats to better locations or upgrading to models with more reliable sensors.
Still Wondering if Your Thermostat Is Bad?
If you’re still wondering how to know if your thermostat is bad, don’t stress—we’re here to help. Whether you live in Vancouver, Orchards, or across the river in Portland, Sub Zero Temp Control is here to help you get to the bottom of your HVAC issues—without the guesswork. From quick fixes to full thermostat replacements, we’ll explain exactly what’s going on and get your comfort system back on track.
Give us a call today to schedule an inspection or thermostat upgrade. You shouldn’t have to wonder if your thermostat is working—let us take care of it for you.
