CT3451 PROGRAMMABLE THERMOSTAT
69-1620—1 10

System Switch

❑The System switch settings control thermostat
operation as follows:
Cool: The thermostat controls the cooling
system.
Off: Both heating and cooling are off.
Heat: The thermostat controls the heating
system.
❑Slide the System switch on the thermostat to the
desired system setting.
Heat and Cool Indicators
indicates a call for heat.
indicates a call for cool.
NOTE: In the programming mode, the and
the indicate System setting.
Minimum Off-Timer
The thermostat minimum off-timer assures that the
compressor does not come on again for at least five
minutes after it turns off.
The minimum off-timer is triggered when the compressor
turns off and when the System switch position is
changed. If the compressor turns off when the setpoint is
changed, the minimum off-timer is triggered.
A flashing snowflake indicates the minimum off-timer
is in effect.

12 CHECK OPERATION AFTER

INSTALLATION/PROGRAMMING

Heating System

❑Slide the System switch to Heat and the Fan switch to
Auto.
❑Press and hold the ▲ key to raise the temperature
several degrees above the room temperature to start
the heating equipment. When using the thermostat
with the Fuel switch set to the E position for electric
heat, the fan starts immediately.
❑Press the ▼ key to lower the temperature setting
below the room temperature. The heating equipment
should shut down.

Cooling System

CAUTION
Compressor Damage Hazard.
Operating at too low of an outdoor
temperature can cause compressor damage.
Do not operate cooling if outdoor temperature is
below 50°F (10°C).
Allow compressor to remain off for five minutes
before restarting.
Refer to manufacturer’s recommendations.
1. Slide the System switch to Cool and the Fan switch
to Auto.
2. Press the ▼ key to lower the temperature setting
several degrees below the room temperature; the
cooling equipment should start. The fan starts and
stops with the cooling equipment.
NOTE: If the cooling system does not start immediately,
remember that the thermostat has a built-in min-
imum off-time of five minutes to protect the com-
pressor.
3. Press the ▲ key to raise the temperature setting
above the room temperature. Cooling system
should shut down.

Fan

❑Slide the System switch to Off and the Fan switch to
On. The fan should run continuously.
❑Slide the Fan switch to Auto. The fan should turn off.

Backlighting

❑Press any key to light the display for approximately
ten seconds.