York YCAL Series - Page 155

FORM 150.66-NM3
ISSUE DATE: 09/25/2020
155
JOHNSON CONTROLS
SECTION 9 - SERVICE AND TROUBLESHOOTING
9
TABLE 32 – TROUBLESHOOTING (CONT’D)
PROBLEM CAUSE SOLUTION
HIGH DISCHARGE PRESSURE FAULT
1. condenser fans not operating or
operating backwards.
1. Check fan motor, fuses and
contactors. Ensure fan blows air
upward.
2. Too much refrigerant. 2. Remove refrigerant.
3. Air in refrigerant system. 3. Evacuate and recharge system.
4. Defective discharge pressure
transducer.
4. Replace discharge pressure
transducer. Refer to “Service”
section for pressure/voltage
formula.
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 ow too low. 3. Increase chilled liquid ow
– refer to “Limitations” in
“Installation” section.
4. Defective LWT or RWT sensor.
(ensure the sensor is properly
installed in the bottom of the well with
a generous amount of heat conductive
compound).
4. Compare sensor against a
known good temperature
sensing device. Refer to
“Service” section 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
understanding 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./
voltage table.
3. Contactor/Overload failure. 3. Replace defective part.
4. Compressor failure. 4. Diagnose cause of failure and
replace.