JOHNSON CONTROLS
118
FORM 145.05-NOM7
ISSUE DATE: 10/31/2019
SECTION 5 – SEQUENCE OF OPERATION
In the figures below, Compressor System
B is used for example only. Other faults
and warnings are found under HISTORY
key and traced back to its specific location
on the Unit Interface.
1. Select HISTORY key, and enter password 9725.
LD21620
2. Select
▼
key and the
◄
key or the
►
key to se-
lect the fault. In this case, "COMPRESSOR B."
LD21621
3. Select
▼
key until the fault is shown. In this case,
the safety chain is open, caused by several factors
(for example high pressure switch, motor protec
-
tion, or a broken wire). Use the wiring diagram to
troubleshoot.
LD21622
4. If the fault is corrected, the compressor must be
programmed back ON. Select the PROGRAM
key, and select the
◄
key or the
►
key to "COM-
PRESSORS," as shown below.
LD21623
5. Push the
key, and the "L" of "LOCKOUT" is
highlighted.
LD21624
6. Select the
◄
key or the
►
key to "RUN," and
push the
key to engage the compressor to run.
LD21625
7. If the fault in the safety chain has been corrected,
the "RUN" state stays on. If it changes back to
"LOCKOUT" immediately, the fault still exists.
LD21626
The compressor might come on when the
compressor state is "RUN" if the cooling
demand is present and it has exceeded its
time delay. There may be other variables
built into the logic on the board that might
delay the compressor from actually run-
ning.
8. Select the COMPRESSOR SYSTEMS key, and
use the
◄
key or the
►
key to "COMPRESSOR
B" if necessary. The status either shows READY
or RUN if all safeties are clear.
LD21627
9. Select
▼
key to display the following if all safe-
ties are met.
LD21628
If the display shows the compressor state
as "COMP ON" and the compressor is
not running, the compressor over amp
protection may be tripped on the motor
starter in the control cabinet.
LD21629
Low Condenser Water Temperature
The Unit Controller monitors the entering water tem-
perature and shut off all active compressors if the en-
tering water temperature drops below the lower limit.
This protects the compressor from damage,
Sequence of Operation
If “COND VALVES INSTALL” option is NONE
or the “COND WATER CONTROL” setting is set
to USER DISABLED, the low limit temperature is
50.0°F. If the “COND VALVES INSTALL” option is
COND ONLY or COND W/ BYPASS and the “COND
WATER CONTROL” setting is set to USER EN-
ABLED, the low limit temperature is 35.0°F
If the “ENT WATER TEMP” falls below the limit
temperature for 30 seconds, a “WRN-LOW WATER
TEMP” is declared and all active compressors are
turned OFF.
If a “WRN-LOW WATER TEMP” is active, it is reset
when the “ENT WATER TEMP” rises above the low
limit temperature plus 1.0°F for 120 seconds.
