69-1052—1
8
T8511G DELUXE HEAT PUMP ZONE THERMOSTAT
5. Press the increase ▲ key again to display the
EEPROM identification code.
6. Press and hold the increase ▲ and decrease ▼
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
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.
(Continued)
M4867
a
Available on select models.
Symptom Possible Cause Action
Display will not
come on.
Thermostat is not being
powered.
• 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.
Thermostat microprocessor is
locked up.
Remove the thermostat from the wallplate for 2 minutes. After
2 minutes, replace the thermostat on the wallplate.
Temperature
display is incorrect.
Room temperature display has
been reconfigured.
Enter Installer Setup number 37 and reconfigure the display.
Thermostat is configured for °F
or °C display
a
.
Enter Installer Setup number 14 and reconfigure the display.
Bad thermostat location. Relocate the thermostat.
Temperature
settings will not
change. (Example:
Cannot set the
The upper or lower temperature
limits were reached.
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).
heating higher or
the cooling lower.)
The setpoint temperature range
stops were configured.
Check Installer Setup numbers 34 and 35 and reconfigure the
setpoint stops.
