York YCAL Series, Installation Operation & Maintenance

Page: 154 / 174

JOHNSON CONTROLS
154
FORM 150.66-NM3
ISSUE DATE: 09/25/2020
SECTION 9 - SERVICE AND TROUBLESHOOTING
TABLE 32 – TROUBLESHOOTING
PROBLEM CAUSE SOLUTION
NO DISPLAY ON PANEL
UNIT WILL NOT OPERATE
1. No 115VAC to 24 VAC Transformer IT. 1a. Check wiring and fuse 1FU.
1b. Check wiring emergency stop
contacts 5 to L of TB1 terminal
block.
1c. Replace 1T.
2. No 24VAC to Microboard. 2. Check wiring 1T to Microboard.
3. 1T defective, no 24VAC output. 3. Replace 1T.
4. Short in wire to temp. sensors or
pressure transducers.
4. Unplug connections at I/O board
to isolate.
5. Defective IPU & I/O board or Display
board.
5. Replace Microboard.
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
manufacturer’s instructions.
3. Defective flow switch. 3. Replace flow switch.
4. Remote cycling device open. 4. Check cycling devices
connected to terminals 13 and
14 of the CTB1 terminal block.
LOW SUCTION PRESSURE FAULT
1. Improper suction pressure cutouts
adjustments.
1. Adjust per recommended
settings.
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 “Installation” section). 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.