Honeywell RTH8500 Guide D'installation page 23

System setup
Manual/Auto changeover
Function
Press
0300
Options: 0 Manual changeover (Heat/Cool/Off).
1 Automatic changeover (Heat/Cool/Auto/Off). Note: System maintains minimum
3°F difference between heat and cool settings.
CAUTION: To avoid possible compressor damage, set to option 0 if the outside
temperature drops below 50°F (10°C).
Temperature format (°F/°C)
Function
Press
0320
Options: 0 Fahrenheit
1 Celsius
Daylight savings time on/off
Function
Press
0330
Options: 0 Off: No adjustment for daylight savings time.
1 On: Auto-change to daylight savings time (through 2006, and for areas that
do not use the new 2007 DST calendar).
2 On: Auto-change to daylight savings time (2007 and beyond, for areas that
use the new 2007 DST calendar).
to select manual or automatic changeover:
s/t
to set the temperature display format:
s/t
to select an option:
s/t

RTH8500