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ComfortSense
t
Model L7742U Touch Screen 7−Day Programmable Thermostat
Appendix B. Diagnostic Information and Hidden Menu Tables
Diagnostic Information Table
Condition
Display Text (Screen1)
Display Text (Screen2)
System Action
Action to Clear / Recovery
Condition
ERROR MESSAGE
AC power loss for more
than 250ms (1/4 second)
Lithium Battery will remember the
clock for 30 days. All outputs will
be off and O/B will remember the
last state.
When AC power is restored, normal
operation resumes.
CPU memory error
OR
ROM error
Note: If either of these er-
rors occur, the display
goes blank and all relays
are disabled.
No Operation
Replace Thermostat
Hi temperature protection:
room temp. exceeds 96F
(35.6C)
All stages of heat are turned off.
If temperature goes down, it will
start working again. (Need to re-
duce temperature in space.)
Local Temp Sensor error:
local temp sensor reads
out of range −40F to 158F
TEMP SENSOR ERROR
CALL FOR SERVICE
Contact Info. Screen
Indoor temp is displayed as "EE"
on the home screen. This will
STOP all temperature related op-
eration.
User − call dealer number from con-
tact information screen and request
thermostat replacement, OR If the
sensor reads back to within the nor-
mal operating range, the error mes-
sage will be cleared. Start working
again.
EEPROM error (Power
ON)
MEMORY ERROR
CALL FOR SERVICE
Contact Info. Screen
System shall restore everything to
ENERGY STAR
®
Default and oper-
ate. If lithium Bat tery has charge, it
will remember the previous stored
settings.
User − call the dealer to replace
thermostat.
EEPROM error (Operat-
ing)
MEMORY ERROR
CALL FOR SERVICE
Contact Info. Screen
System shall operate in normal
mode operation until power off.
User − call the dealer to replace
thermostat.
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