You can fix this
Likely cause: the system lost power
The thermostat gets its power from the furnace or air handler. A switch that's off, a loose door panel or a tripped breaker leaves it blank.
Why this happens
Honeywell lists no power to the HVAC system, a tripped breaker, and an engaged furnace door safety switch among the causes of a blank screen. The door switch cuts power when the front panel isn't fully seated. Honeywell warns never to tape, bypass or disable it.
How to fix it
- Turn the furnace or air handler power switch on.
- Press the front door panel firmly into place so it sits flush. Don't tape or hold the door switch down.
- If the breaker was tripped and held after one reset, leave it on and watch it over the next day.
- Give the thermostat a minute to come back on, then set the mode and temperature you want.
When to stop. If the breaker trips again, leave it off and call an HVAC technician.
If this does not fix it, tell the HVAC technician
- Which was off: the switch, the door panel or the breaker.
- Whether the screen came back once power was restored.
- Whether the breaker has tripped again since.
Build the full list: what to tell the HVAC technician.
Start this troubleshooter over
References (every fact above comes from one of these pages)
Vent, Valve & Volt is published by the team behind FourHome. Browse all FourHome replacement faucet and shower parts on the FourHome Amazon store.