If the thermostat's display is dark, a lack of power may be the issue. Try replacing the batteries, then check for a blown fuse or tripped breaker in the electrical panel. If the thermostat is still unresponsive, make sure the breaker is shut off and remove the cover.
In this case, you'll want to check for the following: Tripped Circuit Breaker: The main issue here is not with the thermostat itself but with the electrical panel. Go to the breaker panel and locate the circuit breaker for your thermostat. If it's off, try to reset the breaker switch.
Depending on your make and model of thermostat, you'll likely see either a small switch on the faceplate or a cycle button between the heating, cooling and off options. You can prep your system to cool your home by moving the switch or pressing the button until you reach the 'cool' setting.
The most common reasons for a blank thermostat screen are dead batteries, a power outage, a tripped circuit breaker, faulty wiring, or a failed thermostat. The screen will be completely dark and unresponsive when there is an issue with power reaching the thermostat.
The common wire, sometimes referred to as the c-wire, is what's responsible for delivering constant power to your thermostat. For programmable and smart thermostats, c-wires are required for setting a heating or cooling schedule.
If your thermostat is blank, the first thing you should do is check the batteries. Chances are, the batteries have died and the thermostat simply can't power on. Replace the batteries and see if your thermostat turns back on. Most thermostats display a low-battery symbol when the juice is running low.
The Thermostat Has No Power
An unresponsive display is a sure sign of thermostat failure. A blank screen indicates dead batteries, a tripped safety switch or a major malfunction in the thermostat's components.
There is usually a small reset button somewhere on the thermostat. Finding this button may require that the thermostat panel be removed and pressing this button may require something like a paperclip to push. Hold the reset button down for 5 seconds and the thermostat should reset.
Place the multimeter's red probe onto the thermostat terminal marked R for red; you can place the black probe onto any of the other terminals. The multimeter reading should be at or close to the thermostat's voltage level.
Try checking the circuit breaker box or replacing the batteries. Bad wiring: The thermostat may be unresponsive if the wiring has gone bad. Remove the cover and check inside for loose, detached, or corroded wires. If you spot any problems, contact an HVAC technician for assistance.
Look for loose wires or relay connections that you can tighten. Or, turn off the breaker to the unit, wait a couple of minutes, and turn it on again (or reset the breaker if it has tripped). The thermostat should start working; if not, it may need to be replaced.
Most modern thermostats will have a clearly marked reset button inside the panel. It's usually small and recessed, so you might need a pointed object like a paperclip to press it. For those wondering specifically how to reset air conditioner thermostat models, the process is generally the same.
Turn your thermostat to the 'off' position... Then venture off to your home's breaker box. Find the breaker to your HVAC system, flipping it 'off'. Make sure the breaker is flipped all the way 'off,' then wait for 30-seconds. Turn the breaker back 'on.
A “No power” alert can be caused by the following: The thermostat wiring is incorrect. Your thermostat is connected to a system that requires a C or common wire, but that wire isn't connected. Some systems, including heat-only, cool-only, zone-controlled, and heat pump systems, require a C wire or Nest Power Connector.
If your thermostat is blank, the first thing you should do is check the batteries. Chances are, the batteries have died and the thermostat simply can't power on. Replace the batteries and see if your thermostat turns on.
Get an Indoor Thermometer
Another way to test your thermostat is to use a thermometer. Place the thermometer in the room and turn on the AC. After a few minutes, check the thermometer to see what temperature it's reading. The temperature should be lower than when you started.
However, when you lose power in your home, it can grow difficult to maintain the perfect temperature. Without power, in the winter your home may become frigid, and in the summer it becomes too hot. Your thermostat becomes effectively useless, as there is no way for it to communicate with their furnace.
A power supply issue is one of the most common culprits behind a blank thermostat screen. Thermostats typically require a constant power supply through batteries or a wired connection. If your thermostat is battery-powered, the first step is to check if the batteries have run out.
Depending on your model of thermostat, you will likely either have a small switch on the thermostat's faceplate or a cycle button to cycle between heating, cooling, and off options. You can prep the system to cool the home by moving the switch or pressing the button until you reach the “cool” setting.