Troubleshooting; Table 27 - Troubleshooting - York YLAA0285SE Manual

SECTION 9 – SERVICE AND TROUBLESHOOTING
TABLE 27 – TROUBLESHOOTING
PROBLEM
No display on panel.
Unit will not operate.
"FLOW SWITCH/REM
STOP NO RUN PERMISSIVE"
"LOW SUCTION PRESSURE"
FAULT
186

TROUBLESHOOTING

CAUSE
1. No 115VAC to 24 VAC
Transformer
2. No 24VAC to Microboard
3. Control Transformer defective, no
24VAC output.
4. Short in wire to temp. sensors
or pressure transducers.
5. Defective IPU II & I/O Board
or the Display Board.
1. No chilled liquid flow.
2. Flow switch improperly
installed.
3. Defective flow switch.
4. Remote cycling device open.
1. Improper suction pressure
cutouts adjustments.
2. Low refrigerant charge.
3. Fouled filter dryer.
FORM 150.72-NM3 (1020)
ISSUE DATE 10/05/2020
SOLUTION
1a. Check wiring and fuse
1FU
b. Check wiring emergency
stop contacts 5 to L of XTBC2
Terminal Block.
c. Replace Control Transformer
2. Check wiring Control
Transformer to Microboard.
3. Replace Control Transformer
4. Unplug connections at IPU II
& I/O Board to isolate.
5. Replace IPU II & I/O Board
or the Display Board.
Contact Johnson
Controls Service
before replacing
circuit boards!
1. Check chilled liquid flow.
2. Check that the flow switch
is installed according to
manufacturer's
instructions.
3. Replace flow switch.
4. Check cycling devices
connected to terminals
13 and 14 of the XTBC1
Terminal Block.
1. Adjust per recommended
settings.
2. Repair leak if necessary
and add refrigerant.
3. Change dryer/core.
CONT'D
JOHNSON CONTROLS