The UCB will flash the last five alarms on the LED. If the compressor is locked out, cancel any call for cool- ing. This will reset any compressor lock outs.
NOTE: While the above step will reset any lockouts, the compressor may be held off for the ASCD. See the next step.
10.If 24 volts is present at the UCB Y1 terminal and none of the switches are open and the compressor is not locked out, the UCB may have the compres- sor in an ASCD. Check the LED for an indication of an ASCD cycle. The ASCD should time out within 5 minutes. Press and release the TEST button to reset all ASCDs.
11.If 24 volts is present at the UCB Y1 terminal and the compressor is not out due to a protective switch trip, repeat trip lock out, or ASCD, the economizer termi- nals of the UCB may be improperly wired. Check for 24 volts at the Y1 “OUT” terminal of the UCB. If 24 volts is present, trace the wiring from Y1 “OUT” for incorrect wiring. If 24 volts is not present at the Y1 “OUT” terminal, the UCB must be replaced.
12.For units without economizers: If 24 volts is present at the Y1 OUT terminal, check for 24 volts at the Y1 “ECON” terminal. If 24 volts is not present, check for loose wiring from the Y1 “OUT” terminal to the
13.For units with economizers: If 24 volts is present at the Y1 “OUT” terminal, check for 24 volts at the Y1 “ECON” terminal. If 24 volts is not present, check for loose wiring from the Y1 “OUT” terminal to the
14.The UCB can be programmed to lock out compres- sor operation during free cooling and in low ambi- ent conditions. These options are not enabled by default. Local distributors can test the UCB for this programming.
For units with factory installed economizers, the UCB is programmed to lock out compressor opera- tion when the LAS set point is reached.
For units without factory installed or with field installed economizers, the UCB allows compressor operation all the time. This programming can be checked or changed by the local distributor.
15.If none of the above correct the error, replace the UCB.
UNIT 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
Current alarms are flashed on the UCB LED. Pressing and releasing the ALARMS 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 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 button once.
TABLE 32: UNIT CONTROL BOARD FLASH CODES
Flash Code | Description | |
On Steady | Control Failure - Replace Control | |
Heart Beat | Normal Operation | |
1 Flash | Not Applicable | |
2 Flashes | Control waiting ASCD1 | |
3 Flashes | HPS1 - Compressor Lock out | |
5 Flashes | LPS1 - Compressor Lock out | |
7 Flashes | FS1 - Compressor Lock out | |
9 Flashes | Ignition Control Locked Out/ | |
Ignition Control Failure / Limit Switch Trip / | ||
| No Jumper Plug in Heat Section | |
|
| |
10 Flashes | Compressors Locked Out On Low | |
Outdoor Air Temperature1 | ||
| ||
11 Flashes | Compressors Locked Out Because the | |
Economizer Is Using Free Cooling1 | ||
| ||
13 Flashes | Compressor Held Off Due To Low Voltage1 | |
14 Flashes | EEPROM Storage Failure (Control Failure) | |
OFF | No Power or Control Failure |
1. These flash codes do not represent alarms.
Johnson Controls Unitary Products | 37 |
