Troubleshooting (Table 6) - Lennox T7300 Installation Instructions Manual

Symptom
Display does not come
on.
Temperature
settings do not change. tti d t h
Heating or cooling does
. .
not come on not come on
Thermostat is calling for
Heat (Heat on) or Cool
(Cool on) but no heating or
cooling is running.
Heat does not turn on
(Heat On is solid in the
display).
Both the heating and cool-
ing equipment are run-
ning at the same time. ning at the same time.
Cooling does not turn on
(Cool On is solid in the dis-
play).

TROUBLESHOOTING (TABLE 6)

Possible Cause
Thermostat is not being
powered.
The upper or lower tempera-
ture limits were reached.
The keypad is fully locked.
Thermostat minimum off−
time is activated.
System selection not set to
Heat or Cool.
System type Selection is in-
correct.
Heating or cooling equip-
ment is not operating.
Heating equipment failure.
Loose or broken wire con-
nection between thermo-
stat and heating equip-
ment.
The heating equipment is
not a heat pump but the
System Type (Installer Set-
up Number 0170) is set to
Heat Pump.
Heating and cooling wires
are shorted together.
Cooling equipment failure.
Loose or broken wire con-
nection between thermostat
and cooling equipment.
Action
Check for 24 Vac between C and Rc.
Check that AAA batteries are installed correctly and are
good.
Check temperature setpoints.
Check Installer Setup Numbers 0600 and 0610; modify as
needed.
Check Installer Setup Number 0670 to change keypad
locked options.
Wait up to five minutes for the system to respond.
Set system Selection to correct position.
Check Installer Setup Number 0170 and make sure cor-
rect System type is chosen.
Check wiring.
Check Installer Setup Number 0170 and make sure cor-
rect system type is chosen.
Verify operation of equipment in System Test mode.
Check for 24Vac at the equipment on the secondary side
of the transformer between power and common. If volt-
age is not present, check the heating equipment to find
the cause of the problem.
Check for 24 Vac between the heat terminal (W) and
transformer common. If 24 Vac is present, the thermostat
is functional. Check the heating equipment to find the
cause of the problem.
Check for 24 Vac between the heat terminal (W) and
transformer common. If voltage is not present, check
wire connection (loose or broken) between the thermostat
and the heating equipment.
Set System Type (Installer Setup Number 0170) to match
the installed heating and/or cooling equipment
Separate the shorted heating and cooling wires.
Check for 24 Vac at the equipment on the secondary side
of the transformer between power and common. If volt-
age is not present, check the cooling equipment to find
the cause of the problem.
Check for 24 Vac between the cool terminal (Y) and trans-
former common. If 24 Vac is present, the thermostat is
functional. Check the cooling equipment to find the cause
of the problem.
Check for 24 Vac between the cool terminal (Y) and
transformer common. If voltage is not present, check
the wire connection (loose or broken) between the ther-
mostat and the cooling equipment.
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