Troubleshooting Guide; Outdoor Temperature Sensor - Honeywell DMULTISTAGE T8524C Installation Instructions Manual

T8524C,D MULTISTAGE MICROELECTRONIC THERMOSTATS
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 will not Thermostat is not being
come on. powered.
Temperature Room temperature display has
display is incorrect. been reconfigured.
Thermostat is configured for °F
or °C display.
Bad thermostat location.
Temperature The upper or lower temperature
settings will not limits were reached.
change. (Example:
Cannot set the
heating higher or
The setpoint temperature range
the cooling lower.)
stops were configured.
a
Available on select models.
69-1055—1
key again to display the
M4866
key again to display the
M6791
Possible Cause
a
5. Press the increase
EEPROM identification code.
(Example: 222 = EEPROM ID 222)
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 five minutes without any key presses.
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 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 wiring between thermostat and HVAC
equipment—replace any broken wires and tighten
any loose connections.
— If 24 Vac is present, proceed with troubleshooting.
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 (7 to 31°C)
• Cooling limits are 45 to 99°F (9 to 37°C) except T8524D
cooling limits are 48 to 99°F
Check Installer Setup mode numbers 34 and 35 and
reconfigure the setpoint stops.
8
key again to display the
and decrease
Action
M4867
(Continued)