Field note
A blank thermostat can be the visible symptom of a float switch opening the 24 V control path.
Trace control power before replacing the thermostat
- Verify transformer output and the control-voltage path.
- Check float switches, wet switches, pump safeties, and drain condition.
- Clear the drain and prove water flows out positively.
Prevent recurrence
- Clean sludge from the pan/line.
- Confirm trap/vent/slope configuration.
- Document recurring biological growth for maintenance follow-up.
Safety / model checks
- Do not jumper a condensate safety and leave the unit unattended.
CondensateThermostatFloat Switch
Safety note
HVAC work can involve high voltage, rotating equipment, pressurized refrigerants, and combustion systems. Use this site as a reference only. Follow the equipment manual, applicable codes, PPE, lockout/tagout, and current refrigerant rules. Field cases and troubleshooting paths are case-specific and are not OEM procedures or universal targets.
Related field cases
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