FORM NO.:6U6K-B01E-NB-EN
JOHNSON CONTROLS
122
TROUBLESHOOTING
TABLE 41 -
TROUBLESHOOTING
SECTION 10 – SERVICE AND TROUBLESHOOTING
PROBLEM
CAUSE
SOLUTION
No display on HMI.
Unit will not operate.
1. No 230VAC to 24VAC Transformer.
2. No 24VAC to Microboard.
3. Control Transformer defective, no
24VAC output.
4. Defective IPU II & I/O Board or the
Display Board.
1 a. Check wiring and power supply.
b. Check wiring emergency stop contacts
of terminal block.
c. Replace Control Transformer.
2. Check wiring Control Transformerto
Microboard.
3. Replace Control Transformer.
4. Replace
& I/O Board or the
Display Board.
C ontact YO R K Service
before replacing circuit
boards!
“Chiller Water Flow”
Fault
1. No chilled liquid flow.
2. Too much air in piping system.
3. Flow switch improperly installed.
4. Defective flow switch.
5. Remote cycling device open.
1. Check chilled liquid flow.
2. Purge the air though a release valve.
3. Check that the flow switch is installed
according to manufacturer’s instructions.
4. Replace flow switch.
5. Check cycling devices connected to
terminals of the terminal Block.
“Low Suction Pressure”
Fault
1. Suction service valve not open or valve
defective.
2. Low refrigerant charge.
3. Fouled or clogged BPHE.
4. EEV defective.
5. Reduced flow of chilled.
6. Defective suction pressure
transducer/low pressure switch or
wiring.
7. Fans not operating (in heating mode).
1. Open or replace suction service
valve.
2. Repair leak if necessary and add
refrigerant.
3. Clean BPHE.
4. Check the wiring, or replace EEV.
5. Check liquid flow rate. Check operation of
pump, clean pump strainer, purge chilled
liquid system of air.
6. Replace transducer/low pressure switch or
faulty wiring.
7. Check fan wiring and communication.
“High Discharge Pressure or
Compressor Overload” Fault
1. Discharge service valve not open or
valve defective.
2. Condenser fans not operating or
operating backwards.
3. Too much refrigerant.
4. Air in refrigerant system.
5. Defective discharge pressure
transducer.
6. Compressor motor locked.
1. Open or replace discharge service valve.
2. Check fan motor, and contactors.Assure
fan blows air upward.
3. Remove refrigerant.
4. Evacuate and recharge system.
5. Replace discharge pressure
transducer.
6. Replace compressor (and oil if
necessary).
IPU3
Cooke Industries - Phone: +64 9 579 2185 Email: [email protected] Web: www.cookeindustries.co.nz
