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Factory Memory Reset
You can use the memory-reset sequence to restore all pro-
grammed functions to the factory default settings:
To restore programmed functions to factory setting:
• Press OFF, SET and FAN simultaneously.
• Press SET.
• After a delay, the memory will be reset from stored values.
After another delay, the display will come back on normally.
Note
If a memory reset is performed, it will be necessary to enable
the auxiliary heat function again (if your system has electric
heat).
Auxiliary (Electric) Heat
(Factory Default: Disabled)
Normally the electric heat function is disabled. If the cooling
unit has electric heat, the function must be enabled to
operate.
To enable or disable electric heat:
• Enter the programming mode: Press OFF, Press SET
• Press HEAT and SET simultaneously.
• Use the UP or DOWN key to enable or disable electric
heat. The code "AH" will be displayed when it is enabled.
A double dash "--" will appear when disabled.
• Press OFF to exit programming mode.
Fahrenheit/Celsius
Display
(Factory Default: Fahrenheit)
You can choose to view temperature in degrees Fahrenheit
or Celsius.
To select Fahrenheit or Celsius:
• Enter the programming mode: Press OFF, Press SET
• Press DOWN, TEMP and UP simultaneously.
• Use the UP or DOWN key to select F for Fahrenheit or C
for Celsius.
• Press OFF to exit programming mode.
Note
Changing from Fahrenheit to Celsius will affect the setpoint
differential and fan response differential, since these settings
are now expressed in degrees Celsius. You should repro-
gram these values following the instructions below.
L-0952 Operation
Setpoint Differential
(Factory Default: 12 = 1.5°)
The setpoint differential is the temperature change needed
for the cooling or heating functions to cycle on and off. The
factory setting of 1.5° Fahrenheit should be adequate for
most applications. Differential selections are available in
increments of 1/8°. Thus, to adjust by one degree, you
should select 8 increments (for 8-eighths).
To program the setpoint differential:
• Enter the programming mode: Press OFF, Press SET
• Press SLOW and FAN simultaneously. The differential will
be displayed.
• Use the UP or DOWN key to change the setting.
• Press OFF to exit the programming mode.
Note
If the temperature display is switched from Fahrenheit to
Celsius, the setpoint differential will also operate on degrees
Celsius. Thus, the factory-set restart differential will be 1.5°
Celsius, which is too wide. To correct this, reset the differen-
tial value from 12 to 6. This will provide a differential of 0.75°
C, or about 1.4° F.
This will also affect the Fan Response Differential, which is
factory set at a value of 4, or 0.5° Fahrenheit. When chang-
ing from Fahrenheit to Celsius, reset the Fan Response
Differential from 4 to 2. This will provide a fan differential of
0.25° C, or about 0.5° F.
Hint
Be careful not to set the restart differential too low, since that
will cause the unit to start and stop more frequently. This will
place an undue load on your electrical system and may
damage the compressor.
Fan Response Differential
(Factory Default: 4 = 0.5°)
When the fan is in the automatic mode, its speed is gov-
erned by how far the room temperature differs from the
setpoint. The fan runs faster when the difference is greater.
As the room cools or warms, the temperature approaches
setpoint, and the fan slows down automatically. The amount
of temperature rise in the room above setpoint needed to
cause the fan to increase in speed one step is called "fan
speed differential". It can be adjusted from 1/4° to 4°, in 1/8°
increments.
The fan speed range is divided by the SMX microprocessor
in five equal increments. If the fan response differential is set
at 1/2°, the fan speed will change 20% for each 1/2° of
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