FORM 201.26-NM1
ISSUE DATE: 1/19/2018
SECTION 9 – SERVICE AND TROUBLESHOOTING
JOHNSON CONTROLS
166
PROBLEM
CAUSE
SOLUTION
HIGH DISCHARGE PRESSURE FAULT
1. Tower fans not operating
1. Check tower.
2. Too much refrigerant.
2. Remove refrigerant.
3. Air in refrigerant system.
3. Evacuate and recharge system.
4. Defective discharge pressure trans-
ducer.
4. Replace discharge pressure
transducer. Refer to Service sec-
tion for pressure/voltage formula.
5. Dirty condenser tubes
5. Clean condenser tubes.
LOW LIQUID TEMP FAULT
1. Improperly adjusted leaving chilled
liquid temp. cutout (glycol only).
1. Re-program the leaving chilled
liquid temp. cutout.
2. Micro panel setpoint/range values
improperly programmed.
2. Re-adjust setpoint/range.
3. Chilled liquid flow too low.
3. Increase chilled liquid flow –
Refer to Limitations in
SECTION 4 - INSTALLATION
.
4. Defective LWT or RWT sensor.
(assure the sensor is properly in-
stalled in the bottom of the well with a
generous amount of heat conductive
compound).
4. Compare sensor against a
known good temperature sens-
ing device. Refer to Service sec-
tion for temp./ voltage table.
MP / HPCO FAULT
1. Compressor internal motor protector
(MP) open.
1. Verify refrigerant charge is not
low. Verify superheat setting of
10° - 15°F (5.6° - 8.3°C). Verify
correct compressor rotation.
Verify compressor is not over
loaded.
2. External overload tripped.
2. Determine cause and reset.
3. HPCO switch open.
3. See High Press. Disch. fault.
4. Defective HPCO switch.
4. Replace HPCO switch.
5. Defective CR relay.
5. Replace relay.
COMPRESSOR(S) WON’T START
1. Demand not great enough.
1. No problem. Consult Installation
Manual to aid in understand-
ing compressor operation and
capacity control.
2. Defective water temperature sensor.
2. Compare the display with a
thermometer. Should be within
+/- 2 degrees. Refer to Service
section for RWT/LWT temp./volt-
age table.
3. Contactor/Overload failure.
3. Replace defective part.
4. Compressor failure.
4. Diagnose cause of failure and
replace.
TABLE 26 -
TROUBLESHOOTING (CONT’D)
Summary of Contents for YCWL0056SE
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