XT300C DELUXE PROGRAMMABLE HEAT-COOL THERMOSTAT
11
69-1212—1
Pub. No. 18-HD25D1-3
TROUBLESHOOTING (
C
ONTINUED
).
Symptom
Possible Cause
Action
Heating will not come
on.
No power to the thermostat.
Check for 24 Vac between R and W 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.
Heating will not come
on.
Thermostat minimum off time is
activated.
Wait up to five minutes for the system to respond.
System selection is not set to
Heat.
Set system selection to Heat.
Heating setpoint is below room
temperature.
Check heating setpoint. Set heating setpoint to desired
temperature.
Cooling will not come
on.
No power to the thermostat.
Check for 24 Vac between R and Y 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 minimum off time is
activated.
Wait up to five minutes for the system to respond. Enter Installer
Setup number 39. Reconfigure minimum off time (if required).
System selection is not set to
Cool.
Set system selection to Cool.
Cool setpoint is above room
temperature.
Check cooling setpoint. Set cooling setpoint to desired
temperature.
Heating or cooling
come on momen -
tarily and shut off
Heat or cool circuit is opening
up or becoming high
impedance.
Add resistor in parallel with load or install interface relay.
System on indicator
(flame=heat,
snowflake=cool)
Fan operation set for 0 (con-
ventional heat) when it should
be set for 1 (electric heat).
Enter Installer Setup number 2 and reconfigure the fan operation.
displays, but no
warm or cool air is
coming from the
registers.
Conventional heating
equipment turns on the fan
when the furnace has
warmed up to a setpoint.
Wait a minute after seeing the on indicator and then check the
registers.
Heating or cooling equipment
is not operating.
Verify operation of heating or cooling equipment in self-test.
Outdoor temperature
not displayed
Option not activated.
Enter Installer Setup number 24 and set to 1. Thermostat must have
OT terminals and a TAYSENS100A installed.
or is incorrect.
Outdoor sensor is connected
incorrectly.
Refer to TAYSENS100A installation instructions and check wiring
between the thermostat and sensor.
Wrong sensor.
Replace sensor with TAYSENS100A sensor.
Filter expired.
Refer to the
Filter Indication section in the Owner’s Guide, Pub.
No. 22-5127-04.
System on indicator
reads Filter and
backlight is flashing.
Filter expired.
Refer to the
Filter Indication section.
Time displaying digits
as three E’s (EEE).
Internal memory failure.
Contact distributor or retailer.
