Troubleshooting Guide - Honeywell CHRONOTHERM IV DELUXE T8624D Product Data

T8624D CHRONOTHERM

TROUBLESHOOTING GUIDE

Refer to Table 12 for troubleshooting information.
Symptom
Display will not Thermostat is not being powered.
come on.
Temperature display Room temperature display has
is incorrect. been reconfigured.
Thermostat is configured for °F or
°C display.
Bad thermostat location.
The upper or lower temperature
Temperature settings
limits were reached.
will not change.
(Example: Cannot set
the heating higher
or the cooling lower.)
The setpoint temperature range
stops were configured.
Heating or cooling Heat or cool circuit is opening up
come on momentarily or becoming high impedance.
and shut off
System on indicator Heating or cooling equipment is
(flame=heat, not operating.
snowflake=cool) is
displayed, but no
warm or cool air is
coming from the
registers.
Heating will not No power to the thermostat.
come on.
Thermostat minimum off time is
activated.
System selection is not set to
Heat.
Heating setpoint is below room
temperature.
68-0166—1
®
IV DELUXE PROGRAMMABLE THERMOSTAT
Table 12. Troubleshooting Information.
Possible Cause
• Check for 24 Vac between R and C 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 48 to 99°F (9 to 37°C) .
Check Installer Setup numbers 34 and 35 and reconfigure the
setpoint stops.
Add resistor in parallel with load or install interface relay.
Verify operation of heating or cooling equipment in system test.
• Check for 24 Vac between R and C 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.
Wait up to five minutes for the system to respond.
Set system selection to Heat.
Check heating setpoint. Set heating setpoint to desired
temperature.
18
Action
(continued)