Why does my thermostat go blank then come back on?

A thermostat display screen that intermittently goes blank and then comes back on points to a loose low-voltage wire connection, a failing transformer, or a loose faceplate mount. If the low-voltage wires (such as the R or C wires) are loosely secured in their terminal blocks at the wall sub-base, minor vibrations from the HVAC system or temperature expansion can briefly interrupt electrical contact, causing the screen to flicker or go blank. Similarly, if the thermostat faceplate does not snap tightly onto the mounting plate, power transmission becomes erratic. Additionally, intermittent power drops from your indoor HVAC transformer can cause temporary reboots. You can troubleshoot by removing the faceplate, tightening all terminal screws, and ensuring secure snap-in seating. You can verify stability when the display stops flickering.