AEC ACOA Series Air-Cooled Central Chillers - Manual (Page 50)

8 Troubleshooting
Symptom Possible cause Solution
Chiller does not start. Power off. Check main disconnect
switch.
Main line open. Check main fuses.
No control voltage. Check control terminal block
for 115 VAC.
Loose terminals. Tighten terminals.
Control circuit open. Check fuses, control
switches, and field-installed
interlocks, pressure and
temperature controls, and
readouts.
Incorrect phase sequence
(UVR option). Reverse incoming power
sequence.
Compressor hums but does
not start. Low voltage. Check at main entrance and
at unit. Consult power
company if voltage is low,
and increase wire size to the
unit if voltage is normal at
main and low at unit. Voltage
must be within 10% of motor
nameplate rating.
No power on one phase of
three-phase unit. Check fuses and wiring.
Compressor cycles on low
pressure control. Refrigerant shortage. Check for leaks and add
refrigerant.
No load on chiller. Check pump operation and
water flow.
Restriction in liquid line. (a) Plugged filter-dryer. If
temperature drop exists
across the dryer, remove
and replace cores.
(b) Liquid line or suction
valve partially closed. Open
valves fully and close in one
full turn.
(c) Expansion valve clogged
or inoperative. Check
superheat setting. Check
charge and thermo bulb.
Head pressure too low. Fan cycle switches set too
low. Check and reset.
ACOA Series Air-Cooled Central Chillers
Page 49