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3. Press the increase
software identification code.
(Example: 02 = software ID code 2)
4. Press the increase
software revision number.
(Example: 001 = revision number 1)
TROUBLESHOOTING GUIDE
Symptom
Display does not
Thermostat is not powered.
come on.
Thermostat microprocessor is
locked up.
Temperature
Room temperature display has
display is incorrect.
been reconfigured.
Thermostat is configured for °F
or °C display (select models).
Bad thermostat location.
Display shows two dashes and
a degree sign.
Temperature
Upper or lower temperature
settings will not
limits were reached.
change. (Example:
Cannot set heating
higher or cooling
lower.)
T7100F MICROELECTRONIC CONVENTIONAL OR HEAT PUMP THERMOSTAT
key again to display the
M4866
key again to display the
M6787
Possible Cause
5. Press the increase
EEPROM identification code.
(Example: 222 = EEPROM ID 222)
6. Press and hold both the increase
decrease
displayed, to exit the Self-Test. The Self-Test times
out after five minutes without any key presses.
• Check that X terminal is connected to the system
transformer.
• Check for 24 Vac between X and R or RH terminals.
— If missing 24 Vac:
— Check if the circuit breaker is tripped—reset the
circuit breaker.
— Check if the system fuse is blown—replace the
fuse.
— Check if the power switch on the HVAC equipment
is in the Off position—set to the On position.
— Check the wiring between the thermostat and the
HVAC equipment—replace any broken wires and
tighten any loose connections.
— If 24 Vac is present, proceed with troubleshooting.
Remove the thermostat from the subbase for 2 minutes. After
2 minutes, replace the thermostat on the subbase.
Enter Installer Setup 37 and reconfigure the display.
Enter Installer Setup 14 and reconfigure the display.
Relocate the thermostat.
Installer Setup 22 is set for remote sensing and the sensor is
missing or the circuit is open or shorted.
Check the temperature setpoints:
• Heating limits are 40 to 90°F (7 to 31°C).
• Cooling limits are 45 to 99°F (9 to 37°C).
7
key again to display the
and the
keys, until the room temperature is
Action
M6788
(continued)
69-0964–2
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