349215-JIM-B-1008
64 Johnson Controls Unitary Products
UNIT CONTROL BOARD FLASH CODES
Various flash codes are utilized by the unit control
board (UCB) to aid in troubleshooting. Flash codes are
distinguished by the short on and off cycle used
(approximately 200ms on and 200ms off). To show
normal operation, the control board flashes a 1 second
on, 1 second off "heartbeat" during normal operation.
This is to verify that the UCB is functioning correctly.
Do not confuse this with an error flash code. To prevent
confusion, a 1-flash, flash code is not used.
Alarm condition codes are flashed on the UCB lower
left Red LED, See Figure 28. While the alarm code is
being flashed, it will also be shown by the other LEDs:
lit continuously while the alarm is being flashed. The
total of the continuously lit LEDs equates to the number
of flashes, and is shown in the table. Pressing and
releasing the LAST ERROR button on the UCB can
check the alarm history. The UCB will cycle through the
last five (5) alarms, most recent to oldest, separating
each alarm flash code by approximately 2 seconds. In
all cases, a flashing Green LED will be used to indicate
non-alarm condition.
In some cases, it may be necessary to "zero" the
ASCD for the compressors in order to perform trouble-
shooting. To reset all ASCDs for one cycle, press and
release the UCB TEST/ RESET button once.
Flash codes that do and do not represent alarms are
listed in Table 27.
TABLE 27: UNIT CONTROL BOARD FLASH CODES
FLASH CODE DESCRIPTION
GREEN
LED
16
RED
LED
8
RED
LED
4
RED
LED
2
RED
LED
1
On Steady This is a Control Failure - - - - -
1 Flash Not Applicable - - - - -
2 Flashes
Control waiting ASCD
1
1.
Non-alarm condition.
Flashing Off Off On Off
3 Flashes HPS1 Compressor Lockout Off Off Off On On
4 Flashes HPS2 Compressor Lockout Off Off On Off Off
5 Flashes LPS1 Compressor Lockout Off Off On Off On
6 Flashes LPS2 Compressor Lockout Off Off On On Off
7 Flashes FS1 Compressor Lockout Off Off On On On
8 Flashes FS2 Compressor Lockout Off On Off Off Off
9 Flashes Ignition Control Locked Out / Ignition Control Failure Off On Off Off On
10 Flashes
Compressors Locked Out on Low Outdoor Air Temperature
1
Flashing On Off On Off
11 Flashes
Compressors locked out because the Economizer is using free
Cooling
1
Flashing On Off On On
12 Flashes Unit Locked Out due to Fan Overload Switch Failure Off On On Off Off
13 Flashes
Compressor Held Off due to Low Voltage
1
Flashing On On Off On
14 Flashes EEPROM Storage Failure Off On On On Off
OFF No Power or Control Failure Off Off Off Off Off
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