Programming
Passport I/O Control Operations Manual
8
L-2231 ENGLISH
P-3: Low Fan Limit
Values for the lower fan-speed limit range from 30 to 75. Set a higher number to increase the fan speed or a lower number to
slow the fan speed.
P-4: Compressor Staging Time Delay
The compressor staging delay is for installations where more than one system operates from the same power source. Setting
different staging delays allows compressors to start at different times when power is interrupted. Stage the units at least five
seconds apart. Minimum delay is five seconds and maximum is 135 seconds. (See “Reversing Valve Operation” on page 3 for
programming tips.)
P-5: Temperature Calibration
This feature calibrates the ambient sensor within a range of ±10°F. Adjust this parameter to display the correct room-
temperature reading. Note that setting increments are in °F even when the control is set to display °C.
P-6: Failsafe Level
There are four failsafe levels. See “Failsafe and Fault-Handling Codes” on page 11 for details.
P-7: Low AC Voltage Shutdown
This control has a built-in voltmeter circuit that monitors the AC input voltage. Depending on whether the input power supply is
115VAC or 230VAC, this parameter can be set to “OFF”, or a number in the range of “75” to “105” (for 115VAC input power) or
“175” to “205” (for 230VAC input power). The factory default setting is OFF.
When this parameter is on, the control checks the AC input voltage prior to each cooling or heating cycle and prevents the
compressor from starting if the voltage is less than the specified setting. This provides extra protection for the compressor and
components within the system during low voltage (brownout) conditions. If this low voltage condition occurs, the fault code
“LAC” appears in the LED display. The fault will continue until the AC input voltage rises above the specified setting, at which
time the LAC fault code clears automatically and the cooling or heating cycle will commence.
After the compressor is started, the low voltage monitor continues to check the AC input voltage. If it drops below the specified
setting and remains below for 5 minutes, the system will shut down and the “LAC” fault will be displayed. The system will remain
shut down until the voltage goes back above the specified setting. Once the voltage is restored, after the normal fault recovery
delay, the system will be restarted. As with all faults, system lockout (sustained shutdown) will occur after the fourth consecutive
LAC fault. See “Failsafe and Fault-Handling Codes” on page 11 for further details on system lockout..
P-8: De-Icing Cycle
The de-icing cycle prevents ice build up on the evaporator coil during extended periods of cooling operation. Installation
variables such as grille sizes, length of ducting, insulation, and ambient temperatures determine the run time required to
achieve set point. Factors that substantially increase run time include operating the system with hatches and doors open, and
programming an unrealistic set point (e.g. 65°F/18.3°C). Such situations can cause the evaporator to form ice on warm humid
days.
•
For software revision A13 and older,
de-icing is accomplished by switching the reversing valve into Heat Mode while
the system is cooling. The valve remains energized for the programmed cycle time. The cycle is programmable to
“OFF” or to a period of 1, 2, or 3 minutes.
•
For software revision A21 and newer,
de-icing is accomplished by closely monitoring the room air temperature in 10-
minute intervals during a cooling cycle. Depending on the parameter value and the change in room temperature during
these monitoring intervals, the control performs various actions to prevent ice from forming or to melt ice that has
already formed. This is accomplished by short compressor shutdown periods combined with a one-speed increase in
fan speed, and by periodic Heat Mode cycles with the fan turned off.
The parameter setting for the de-icing feature depends on whether you are using the optional alternate air-temperature sensor
or the display’s built-in room air-temperature sensor. Installation of an optional alternate air temperature sensor (located in the
return air path) greatly increases the effectiveness of the de-icing feature, and this option should be considered whenever the
display sensor cannot read the room temperature accurately.
•
If using an optional remote air-temperature sensor,
set this parameter to “1” to turn the de-icing feature on, or to
OFF
to disable.
•
If using the display’s built-in room air temperature sensor,
this feature has two selectable behavior modes. Both
modes attempt to compensate for any temperature discrepancy the display sensor experiences. (Although
discrepancy is not typical, installation variables such as where the display is placed inside the room—near an open
door or in direct sunlight—can affect how accurately it reads the actual room temperature.) Set this parameter to “1” to
assume the display sensor may be reading the room temperature as much as 5°F (2.8°C) greater than the actual
IMPORTANT
Once the high and low fan speed limits are set, the unit automatically readjusts the remaining speeds to produce six
equally spaced fan speeds in both Automatic and Manual Fan Modes.
Summary of Contents for Passport I/O
Page 23: ...NOTES...
