Thermostat blank / no display

Controls / thermostat

AirCompDX - Field Reference for Air Compressor Techs
All HVAC symptoms
1

Dead batteries

low
CheckBattery indicator or measure at terminals.
FixReplace with fresh alkalines.
2

Blown 24 V fuse on control board

med
Check3 A ATC fuse on board — check continuity.
FixFind short in thermostat cable; replace fuse.
3

Float switch tripped (safety)

med
CheckFull condensate pan or plugged drain.
FixClear drain, flush with vinegar; reseat float.
Safety

Pull the disconnect and lock out before opening HVAC equipment. Discharge dual-run capacitors before handling. Refrigerant recovery and brazing require EPA 608 certification and proper PPE.