Honeywell Electronic Programmable Thermostat Owner's Manual page 11

INSTALL TWO AA ALKALINE
BATTERIES AS SHOWN
TU
Auto On
Fan
FAN SWITCH
AM
LEAVE
Cool Off Heat
System
SYSTEM
SWITCH
M5782
If the batteries are not replaced sometime
during the flashing bAt Lo, the indicator
eventually stops flashing. bAt Lo stays on
without flashing, indicating the thermostat and
heating/cooling system stopped working and
the batteries are almost completely dead.
After the batteries are completely dead, the
bAt Lo indicator disappears, leaving a com-
pletely blank display.
To remove, press down on left ends of
batteries. If the new batteries are installed
within 20 to 30 seconds of removing the old
ones, the thermostat does not have to be
reprogrammed. If the display is blank, the
batteries are dead or incorrectly installed, the
thermostat has to be reprogrammed. See
Programming Your Thermostat section for
instructions.
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