41
Reversing Valve Operation
The reversing valve will enable if the
controller receives a 24VAC input on the
“O” terminal and the compressor has been
operational for a minimum of 5 seconds.
The default reversing valve position is for
heating operation, no 24VAC input on the
“O” terminal. Therefore, in compressor
cooling operation 24VAC must be applied to
the “O” terminal.
Random Start Delay
The controller will enter a random start
delay in these situations:
1) The unit powers up
2) Recovery from emergency shutdown
alarm
3) Recovery from high voltage alarm
4) Recovery from low voltage alarm
5) Night setback mode is disabled
The random start delay will be between 3
and 60 seconds. The fan and compressor
will not be operational during this time. The
random start delay will be ignored if the unit
is in test mode.
Building Occupancy Status
Occupied Mode
The controller will operate according to the
thermostat inputs.
Night Setback Mode
Night setback mode is enabled upon
receiving a 24VAC or a 24VAC common
input on the “NS” terminal. While in night
setback mode the controller will ignore the
normal thermostat signals. Instead the
controller will use the “NS_TH” input as the
fan and compressor enable signal operating
at full compressor capacity. When the unit
is taken out of night setback mode the
controller will execute a random start delay.
The night setback mode can be overridden
with a 24VAC input to the night setback
override terminal “NS_OV”. Once the
override signal is received, night setback
will be overridden for 2 hours even if the
signal is removed. While night setback is
overridden the controller will respond to the
normal thermostat signals.
Test Mode
Test mode is enabled by connecting the two
quick disconnect terminals “TEST” and
“TEST IN” together. The controller will
remain in “Test Mode” as long as the
terminals are connected to each other. The
controller will exit “Test Mode”
immediately upon removal of the jumper.
While in “Test Mode” there will be no
random start delay, and the compressor
minimum on and minimum off times are
reduced to 5 seconds each. The 5 second
delay between compressor and reversing
valve operation is still present as well as the
5 second delay between the supply fan and
compressor.
Alarms
LED Fault Codes
The controller provides a status LED (D5) in
the center of the board to indicate the unit
status. A green status light indicates that the
unit is powered up and that the controller is
not detecting any fault conditions. A
flashing red status light indicates that the
controller has detected a fault condition and
is now in alarm mode. The number of
flashes indicates what alarm is present.
Table 8 describes the meaning of the flash
codes.
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