York Millennium YCAJ150, Installation Operation & Maintenance, Page: 112 / 116

112 YORK INTERNATIONAL
“Low Suction” Fault 1. Improper Suction Pressure Cut-out 1. Adjust per recommended settings and
adjustment. restart unit.
2. Low refrig. charge. 2. Repair leak / add refrigerant.
3. Fouled filter drier. 3. Change drier core.
4. Thermal expansion valve adjust- 4. Adjust compressor suction superheat to
ment / failure. 11°F (6.1°C) or replace power element
(or valve).
5. Reduced flow of chilled liquid 5. Check GPM (See OPERATING LIMIT-
through cooler. ATIONS) Check operation of pump.
Clean pump strainer, purge chilled liquid
system of air.
6. Defective suction press. transducer. 6. Replace transducer.
7. Fouled compressor suction strainer. 7. Remove and clean strainer.
8. Faulty wiring to transducer. 8. Check wiring.
“High Dsch” Fault 1. Condenser fans not operating or 1. Check fans, fuses, and contactors.
Cuts out on High Dis- rotating backwards.
charge Pressure as 2. Too much refrigerant. 2. Remove refrigerant.
sensed by Micropro- 3. Air in Refrigerant System. 3. Evacuate and recharge.
cessor via high dis- 4. Defective discharge pressure 4. Replace discharge pressure transducer.
charge pressure transducer.
transducer. 5. Assure Programmable H.P. Cut-out 5. Adjust per recommended settings and
is correctly set. restart unit.
NOTE: If external H.P.
6. Assure OAT sensor is reading 6. Place a thermometer next to the sensor
Cut-out Switch opens,
properly. and compare reading to the display. Op-
a “Motor Current” Fault
eration should not suffer if thermometer
will result.
is +/– 10°F (5.5°C).
“Chiller Fault: High 1. Temperature sensed incorrectly 1. Verify actual ambient temperature at probe
Ambient Temp” by thermistor. +/– 10°F (5.5°C) with a thermometer placed
Cuts out on high ambi- next to the OAT sensor.
ent temperature. 2. Fans rotating backwards. 2. Air flow must be up. Correct fan rotation.
(Max. = 130°F [54.4°C] 3. Air flow to unit restricted (or being 3. Check installation clearances.
will restart automatically re-circulated). (See pages 10 and 11).
if temperature drops 4. High ambient cut-out set too low. 4. Reprogram cut-out.
below 128°F [53.3°C]).
“Chiller Fault: Low 1. Temperature of outside air is below 1. No problem exists.
Ambient Temp” cut-out setting.
Cuts out on low 2. Temperature sensed incorrectly by 2. Verify actual ambient temperature imme-
ambient temperature. thermistor. diately at probe with thermometer.
(25°F [-3.9°C] min. for 3. Check low ambient temperature 3. Adjust if necessary.
std. adjustable for low Cut-out setting on the display.
NOTE: For occasional operation below
ambient unit)
0°F (-17.8°C) set the cut-out at 0°F
NOTE: Operation below (17.8°C). The chiller is then allowed to
25°F (-3.9°C) requires operate regardless of temperature. A low
low ambient accessory. ambient kit must be installed.
“Chiller Fault: Low 1. RWT Control ONLY: Control range 1. Flow is lower than design. Increase flow or
Water Temp” is too small and does not match increase the control range to match actual
actual
∆
T across evaporator under evaporator
∆
T.
Low water temperature full load conditions.
shutdown 2. Check LWT cut-out point on panel. 2. Adjust if necessary, and restart unit.
(See page 45).
PROBLEM CAUSE SOLUTION