FORM 145.16-IOM2 (0611)
14 JOHNSON CONTROLS
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 (5) 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 anti-short cycle delays
(ASCD) 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.
Flash Codes Description
On Steady Control Failure – Replace Control
Heart Beat Normal Operation
2 Flashes Control Waiting on ASCD
1
(Anti-Short Cycle Delay)
3 Flashes HPS1 – Compressor Lock out
5 Flashes LPS1 – Compressor Lock out
13 Flashes Compressor Held OFF due to Low Voltage
1
14 Flashes EEPROM Storage Failure (Control Failure)
15 Flashes Condensate Overflow Switch – Compressor Lock out
16 Flashes Coaxial Freeze Thermostat – Compressor Lock out
1. These flash codes do not represent alarms.
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