What to Do If Your Thermostat Has No Power

What to Do If Your Thermostat Has No Power

A broken thermostat can put a damper on home comfort. Fortunately, the problem may simply be that your thermostat has no power. Let’s cover how to bring a powerless thermostat back to life.

Is the thermostat turned on?

Before you panic about your thermostat not getting power, first make sure it’s turned on. Set the dial to “heat” or “cool” and the fan to “auto.” Then, for heating, make sure the target temperature is set higher than the current ambient temperature. For cooling, the target temperature should be lower than the current ambient temperature.

Has a circuit breaker tripped?

If the thermostat screen is blank, you likely have a power issue. Assuming there isn’t a power outage, the electrical box is the first place to check. If the circuit breaker that powers the thermostat has tripped, the thermostat will go dark. Reset any tripped breakers you find to see if that solves the issue.

Has a fuse blown?

Some thermostats have a fuse inside that acts as a protection against power surges. Occasionally, these fuses blow or go bad. To check the fuse, take off the thermostat’s cover. Inside the device, you’ll see a clear canister with metal ends. This is the fuse, which should feature a filament running the length of it. If the filament is broken, you must replace the fuse for the thermostat to work again.

Are the batteries dead?

Most electronic thermostats, including programmable models, run on battery power. Remove the cover and examine the back of it for instructions on where the batteries are located. If you can’t find them, check the owner’s manual.

Is the thermostat failing to send a signal?

Sometimes, a thermostat will receive power, but it won’t send a signal to the furnace or air conditioner. To determine if this is the problem, you must test your thermostat. Unless you feel comfortable tinkering with electrical devices, we recommend calling a professional to handle this task for you. If you decide to test the thermostat yourself, follow these DIY tips to ensure your safety:

  • Shut off the power: Make sure your thermostat isn’t receiving power by flipping the circuit breaker. Failure to follow this step could result in electric shock.
  • Remove the cover: Take the front cover off the thermostat to expose the internal wiring.
  • Take a photo: It’s wise to snap a picture of the wiring the way it is now before you start disconnecting anything. This way, you can more easily put it back together.
  • Unscrew the wires: Find one wire labeled “R” (or “Rh”) and another labeled “W.” Loosen the screws and remove the wires from underneath.
  • Connect the wires: Twist the ends of the two wires together, and then flip the circuit breaker to restore power to the thermostat. If the furnace or air conditioner starts running, this means the thermostat is not sending the appropriate signals. If the HVAC system remains quiet, it means the thermostat is working fine, but the AC or heater could be malfunctioning.
  • Put the thermostat back together: Now do everything in reverse—flip the circuit breaker, untwist the wires, screw them back into position, put the cover back on, and restore power to the thermostat.

Get More Help From Aire Serv®

If these tips don’t fix your broken thermostat, it’s time to call a professional. A repair may be enough to fix the issue. Otherwise, you might need to replace your thermostat. Think of this as your chance to upgrade to a WiFi thermostat with advanced capabilities.

For answers to more thermostat questions, or to schedule repair services, please contact Aire Serv today.