Why Is My Thermostat Not Working?

If you wake up in a sweat or to a house so cold you can see your breath, don’t panic. If you’re lucky, it’s simply a problem with your home’s thermostat and you can get your home comfortable again quickly.

Your HVAC thermostat is the brains of your residential HVAC system. Once you choose a set temperature for heating or cooling, thermostat sensors measure the indoor temperature and the thermostat signals the furnace, heat pump, or air conditioner to raise or lower the temperature.

Whenever there’s a problem with your heating and cooling, checking to see if your thermostat is communicating with your HVAC system is a good first step. It’s something you as a homeowner can do pretty easily. For larger issues, you will need to contact an HVAC professional. 

These issues can apply to just about any thermostat. The solutions we discuss will apply to Trane thermostats including smart thermostats, programmable thermostats, and non-programmable thermostats. For more information, refer to your thermostat owner’s manual.

If you have another thermostat brand, refer to the owner’s manual. They’re usually available online if you don’t have the original manual.

A blank thermostat display indicates no power to the thermostat. If your thermostat uses batteries, try removing the cover and replacing the batteries. If it is a wired thermostat, there may be a problem with the thermostat wiring. Unless you’re an HVAC technician or electrician, we don’t recommend fiddling with the wires. Call an HVAC professional for assistance.

You can also try checking the circuit breaker. The thermostat is connected to the same breaker that supports your HVAC system. If the breaker is tripped, contact an HVAC service provider. A heating or cooling system problem caused the breaker to trip. Flipping it back on and turning on the system could cause damage. The problem needs to be resolved before turning the system back on. 

For an old thermostat without a digital screen that won’t turn on, either the thermostat wiring is bad or the thermostat itself has died. Consider thermostat replacement and upgrade to a smart thermostat or at the very least, a programmable thermostat. Learn how to pick the right thermostat for your home.

If your HVAC system is working properly but the temperature readings displayed on the thermostat doesn’t match the temperature in your home, there could be several causes.

• Thermostat placement Does the sun shine through a window and directly onto your thermostat? This will cause it to tell the AC to run or the furnace to stop, depending on the season. An important part of thermostat installation is proper placement. A thermostat should be placed out of direct sunlight, away from the kitchen, and not directly above or below a supply register.
• Faulty wiring Loose, corroded, or chewed thermostat wiring can cause your thermostat to stop working, or work intermittently, which can result in incorrect temperature displays. You may be able to identify corroded or loose wiring by taking the faceplate off of the thermostat housing.   Call a professional to fix bad wiring. 
• Dead or dying batteries If your thermostat operates on batteries, try replacing them. If new batteries don’t help it show the correct temperature, try the other troubleshooting.
• Failing thermostat A failing thermostat may also result in an incorrect temperature display. If you’ve tried the other troubleshooting and your thermostat is older, it may be time to replace the thermostat. 

Learn about Trane’s best thermostats.

If this is happening, it may be due to any of the reasons we just mentioned. Check the placement, the wiring, and the batteries, if applicable. If the thermostat seems OK, the problem may be with your air conditioner or heat pump. 

If thermostat troubleshooting doesn’t fix the problem, move on to air conditioner troubleshooting or heat pump troubleshooting. You may need to call for HVAC service to schedule AC repair. 

Again, try the thermostat troubleshooting tips from the first sections. If you determine there’s nothing wrong with the thermostat, move on to gas furnace troubleshooting or heat pump troubleshooting, based on your system. You may need to call for HVAC service to schedule AC repair. 

Call your local Trane dealer for assistance if your thermostat stopped working and you can’t figure out why. If it’s a Trane smart thermostat and you have granted Trane Diagnostics remote access, they may be able to troubleshoot the issue and fix it remotely.

If you need to replace the thermostat or have other HVAC issues, they can also schedule an on-site visit to get your HVAC system operating as it should.

Anne Fonda, Content Writer at Trane Technologies

A Content Writer with Trane Technologies, Anne Fonda researches topics and writes for Trane® and associated residential HVAC brands. She works in collaboration with Trane Technologies subject matter experts, offering easy-to-understand, informative content on complex topics. Her goal is to help consumers make informed decisions on the products and services they need.

She has written for HVAC and other service provider websites for over 16 years. Before transitioning to web content writing, Anne had a 14-year stint as an award-winning journalist. She graduated cum laude from the University of Missouri-Columbia School of Journalism. When she’s not working, Anne enjoys playing word games, reading, gardening, spending time with family, and visiting gardens and museums.

Expert review by Michael Morey, Smart Thermostat Product Manager

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