AEC NEC Central Station Air and Water Cooled Chiller - Manual (Page 48)

NEC Series Water- and Air-Cooled Central Chillers Page 47
7 Troubleshooting
Problem Possible Cause Solution
Unit does not run. No power. Check main disconnect,
fuses, wiring, and power lead
to unit.
Wrong voltage supplied to
unit. Voltage must be within plus
or minus 10% of nameplate
rating.
Defective on/off switch. Replace.
Control circuit fuse blown. Replace, check transformer.
Check crankcase heater.
Defective control transformer. Replace.
Flow switch circuit is open. Check auxiliary pump for
proper rotation.
Pump motor off on overload. Reset and test.
Auxiliary pump runs;
compressor does not. Freeze control set higher
than temperature of liquid in
system. Lower freeze control setting
to 10°F below desired
leaving temperature.
Defective freezestat. Replace.
Refrigerant low. Check refrigerant charge.
Oil pressure switch Reset oil pressure switch.
contacts are open. Run unit and check oil
pressure.
Refrigerant high pressure Clean the air filters.
cutout switch contacts are
open. Check condenser fans for
proper rotation.
Check for dirty condenser.
Check for condenser air
obstruction.
Fan motor out on overload. Reset and test.
Defective fan cycling control. Replace.
Defective fan motor. Repair or replace.
Compressor internal overload
open. Allow time to cool and reset,
then check for high/low
voltage. Voltage must be
within plus or minus 10%
of nameplate rating. Check
for poor compressor
electrical connections.
Compressor contactor
holding coil open.
Repair or replace.
Broken wire in the
compressor control circuit. Locate and repair.