SECTION 9 – SERVICE AND TROUBLESHOOTING
FORM 201.26-NM1
ISSUE DATE: 1/19/2018
JOHNSON CONTROLS
165
9
TROUBLESHOOTING
TABLE 26 -
TROUBLESHOOTING
PROBLEM
CAUSE
SOLUTION
NO DISPLAY ON PANEL
UNIT WILL NOT OPERATE
1. No 115VAC to 24 VAC Transformer.
1a. Check wiring and fuse 1FU.
1b. Check wiring emergency stop
contacts 5 to L of TB1 terminal
block.
1c. Replace Control Transformer
2. No 24VAC to Microboard.
2. Check wiring Control Transform-
er to Microboard.
3. Control Transformer defective, no
24VAC output.
3. Replace Control Transformer.
4. Short in wire to temp. sensors or pres-
sure transducers.
4. Unplug connections at IPU II &
IO board to isolate.
5. Defective IPU II & I/O board or Display
board.
5. Replace IPU II & IO board or the
Display Board.
Contact Johnson
Controls Service
before replacing
circuit boards.
FLOW SWITCH/REM
STOP NO RUN PERMISSIVE
1. No chilled liquid flow.
1. Check chilled liquid flow.
2. Flow switch improperly installed.
2. Check that the flow switch is
installed according to manufac-
turer’s instructions.
3. Defective flow switch.
3. Replace flow switch.
4. Remote cycling device open.
4. Check cycling devices connect-
ed to terminals 13 and 14 of the
CTB1 terminal block.
LOW SUCTION PRESSURE FAULT
1. Improper suction pressure cutout
adjustments.
1. Adjust per recommended set-
tings.
2. Low refrigerant charge.
2. Repair leak if necessary and add
refrigerant.
3. Fouled filter dryer.
3. Change dryer/core.
4. TXV defective.
4. Replace TXV.
5. Reduced flow of chilled liquid through
the cooler.
5. Check GPM (See Limitations in
SECTION 4 - INSTALLATION
).
Check operation of pump, clean
pump strainer, purge chilled
liquid system of air.
6. Defective suction pressure transducer/
low pressure switch or wiring.
6. Replace transducer/low pressure
switch or faulty wiring. Refer to
Service section for pressure /
voltage formula.
7. LLSV defective.
7. Replace LLSV.
Содержание YCWL0056SE
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