430648-JIM-D-1010
Johnson Controls Unitary Products
25
Figure 14: 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.
Table 11: J10 thru 20YD 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
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
2
Off
Off
On
On
On
8 Flashes
FS2 Compressor Lockout
2
Off
On
Off
Off
Off
10 Flashes
Compressors Locked Out on Low Outdoor Air Temperature
1
Flashing
On
Off
On
Off
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
1. Non-alarm condition.
2. Freeze Stat not applicable.
Check
Alarm
History
Reset All
ASCDs for
One Cycle
Non Alarm
Condition Green
LED Flashing
Current Alarm
Flashed
Red LED
