Thermostat Screen Blank?
No display doesn't always mean big problems. Check these 3 things first.
Replace the Batteries
Most digital thermostats use AA or AAA batteries. When they die, the screen goes blank—even if your HVAC system is fine. This is the #1 cause of blank thermostat screens.
The Fix
Pop off the thermostat cover and replace the batteries. Use fresh alkaline batteries, not rechargeable. Wait 30 seconds for the screen to boot up.
Check the Breaker
Some thermostats are hardwired to the HVAC system. If the breaker tripped, both the thermostat and the system lose power. Check your electrical panel.
The Fix
Find the HVAC breaker (usually labeled "Furnace," "AC," or "HVAC"). If it's tripped, flip it fully OFF, then back ON. If it trips again immediately, call a tech.
Check the Furnace Door
Furnaces have a safety switch that cuts power when the access door is open or not seated properly. If someone was recently working on the furnace, the door might be ajar.
The Fix
Go to your furnace and make sure the access panel is fully closed. Press firmly—you should feel it click into place. The safety switch should re-engage.
Still Blank?
Could be a blown fuse on the control board, bad transformer, or faulty thermostat. These need a professional diagnosis.