Honeywell ENERGYPRO T8665D - Manual (Page 43)

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TROUBLESHOOTING (TABLE 3)
Table 3. Troubleshooting.
Symptom Possible Cause Action
Display does not
come on.
Thermostat is not being
powered.
Check if the thermostat is mounted and
latched on the wallplate—mount and latch
the thermostat on the wallplate.
Check if the circuit breaker is tripped—
reset the circuit breaker.
Check if the fuse at the fuse box is
blown—replace the fuse.
Check if System switch at equipment is in
the Off position—set to On position.
Check if batteries are correctly installed—
be sure they are fresh and installed
correctly. Replace them, if necessary.