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T8501D DELUXE ZONE THERMOSTAT
5. Press the increase
EEPROM identification code.
6. Press and hold the increase
keys together, until the room temperature is
displayed, to exit the system-test. The system-test
times out after ten minutes without any key presses.
TROUBLESHOOTING GUIDE
Symptom
Display will not
Thermostat is not being
come on.
powered.
Thermostat microprocessor is
locked up.
Temperature
Room temperature display
display is incorrect.
has been reconfigured.
Thermostat is configured for
°F or °C display.
Bad thermostat location.
The upper or lower
Temperature
temperature limits were
settings will not
reached.
change. (Example:
Cannot set the
heating higher or
The setpoint temperature
the cooling lower.)
range stops were configured.
a
Available on select models.
69-1049—1
key again to display the
M4867
and decrease
Possible Cause
a
CHECKOUT
Outdoor Temperature Sensor
(Where Applicable)
Allow the outdoor temperature sensor to soak in the
outdoor air for a minimum of five minutes before taking a
reading. With an accurate thermometer (±1°F [±0.5°C]),
measure the temperature at the sensor location, allowing
time for the thermometer to stabilize before reading. Match
the thermometer reading to the outdoor temperature
display at the thermostat.
• Check that C terminal is connected to the system transformer.
• Check for 24 Vac between C and R 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 wiring between thermostat and HVAC
equipment—replace any broken wires and tighten
any loose connections.
— If 24 Vac is present, proceed with troubleshooting.
Remove the thermostat from the wallplate for 2 minutes. After
2 minutes, replace the thermostat on the wallplate.
Enter Installer Setup number 37 and reconfigure the display.
Enter Installer Setup number 14 and reconfigure the display.
Relocate the thermostat.
Check the temperature setpoints:
• Heating limits are 40 to 90°F (4.5 to 32°C)
• Cooling limits are 48 to 99°F (7 to 35°C).
Check Installer Setup numbers 34 and 35 and reconfigure the
setpoint stops.
8
Action
(Continued)
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