Honeywell T8665A Owner's Manual - Page 41

TROUBLESHOOTING Symptom Display does not come on. Possible Cause Thermostat is not being powered. Temperature setting does not change (Example: cannot set the heating higher or the cooling lower). Heating does not come on. The upper or lower temperature limits were reached. System selection is not set to Heat. Heating setpoint is below room temperature. "Filter" flashes in display. Indicates a Filter Timer has expired. Action • Check if the batteries are correctly installed. • Check if the thermostat is mounted and latched on the wallplate-mount and latch the thermostat on the wallplate. Check that the temperature setpoints are: Heating: 40 to 90°F (4 to 32°C) Cooling: 55 to 99°F (13 to 37°C). Check that setpoint is above room temperature. Check if the circuit breaker is tripped-reset the circuit breaker. Check if the fuse at your fuse box is blown-replace the fuse. Check if the System switch at the equipment is in the Off position-set to the On position. Wait five minutes for the system to respond (thermostat displays " Wait"). Set System selection to Heat. See Display or Reset Filter Timer Settings section to reset timer. continued 41 69-1536-3