Microprocessor control unit flash codes
Various flash codes are utilized by the microprocessor control 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 boards flash a 1 second on, 1 second off “heart beat”
during normal operation. This is to verify that the microprocessor is functioning correctly. Do not
confuse this with an error flash code. To avoid confusion, the 1-flash fault code is not used.
Current alarms or active restrictions are flashed on the microprocessor control LED.
1. LAST ERROR – When this button is pressed and released, it flashes the last five flash codes on
the board’s LED. The most recent alarm is shown first and the oldest alarm is shown last.
2. TEST RESET – When this button is pressed and released, any ASCDs are bypassed for one
cycle. When pressed twice, any active lockouts are reset.
3. COMM SETUP – If the board is to be networked with other units, this button is used to set
the network address. Press the button once and it scans the bus, then assigns itself the first
available address (starts at 2). It then flashes that address one time. Pressing the button
twice causes the control to flash the address.
Table 16: Controller flash (fault) codes
Flash codes
Description
On steady
Control failure
2 flashes
Control waiting anti-short cycle delay (ASCD)*
3 flashes
High pressure compressor 1 lockout
4 flashes
High pressure compressor 2 lockout
5 flashes
Low pressure compressor 1 lockout
6 flashes
Low pressure compressor 2 lockout
7 flashes
Condensate overflow switch lockout
11 flashes
Compressor(s) locked out due to economizer running (free cooling)*
13 flashes
Compressor held off due to low voltage
14 flashes
EEPROM storage failure
OFF
No power or control failure
Note:
Flash rates marked with * are NOT alarms.
67
C-Series Vertical (CSV) Water-Cooled Self-Contained Units, B Generation, R-410A Installation, Operation, and
Maintenance Manual
