JOHNSON CONTROLS
212
FORM 150.67-NM1
ISSUE DATE: 4/28/2017
SECTION 9 – SERVICE AND TROUBLESHOOTING
TABLE 37 - TROUBLESHOOTING
PROBLEM CAUSE SOLUTION
NO DISPLAY ON PANEL
UNIT WILL NOT OPERATE
1. No 115VAC to 24VAC 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
Transformer to Microboard.
3. Control Transformer defective, no
24VAC output.
3. Replace Control Transformer.
4. Short in wire to temperature sensors
or pressure transducers.
4. Unplug connections at IPU II and
I/O board to isolate.
5. Defective IPU & I/O board or the
Display board.
5. Replace IPU & I/O board or the
Display board.
Contact Johnson
Controls Service
before replacing
circuit boards.
FLOW SWITCH/REM
STOP NO RUN PERMISSIVE
1. No chilled liquid ow. 1. Check chilled liquid ow.
2. Flow switch improperly installed. 2. Check that the ow switch
is installed according to
manufacturer’s instructions.
3. Defective ow switch. 3. Replace ow 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 lter dryer. 3. Change dryer/core.
4. TXV defective. 4. Replace TXV.
5. Reduced ow 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.
To Next Page
Loading...
Need help?
General
