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5.8 TROUBLE SHOOTING
SYMPTOM POSSIBLE CAUSE REMEDY
1. Unit will not
start
1. Power off
2. Main line open
3. Incorrect wiring
4. Loose terminals
5. Control circuit open
1. Check main disconnect switch.
2. Check main fuses.
3. Check with wiring diagrams.
4. Tighten terminals.
5. Check pump fuses, starter heater elements,
pressure and temperature controls.
2. Compressor
hums but
does not
start
1. Low voltage
2. No power on one phase
of 3 phase unit
3. Faulty starter or
contactor
1. 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.
2. Check fuses and wiring.
3. Check the contacts and time delay on part wind
start.
3. Compressor
cycles on
low
pressure
control
1. Refrigerant shortage
2. No load on chiller
3. Restriction in liquid line
4. Head pressure too low
1. Check for leaks and add refrigerant.
2. Check pump operation and water flow.
3. a.) Plugged drier. If temperature drop exists across
the drier 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.
4. Restrict water flow to condenser by adjusting the
water regulating valve or cycle cooling tower fan.
4. Compressor
cycles on
high
pressure
control
1. Compressor discharge
valve partially closed.
2. Air in system
3. Overcharge of
refrigerant
4. High pressure control
improperly set
5. Main water valve closed
6. Water regulating valve
set high or defective
7. Condenser fan
inoperative
8. Dirty condenser
9. Fan cycle switches in-
operative, or set too
high
10. Fan motors not running
11. Fan motor reverse
rotation
1. Open valve fully and close with one turn
2. Flush water valve. If pressure in system exceeds the
pressure corresponding to the water temperature
purge air from compressor gauge connection.
3. Purge system while in operation until bubbles show
in sight glass. Close valve and add small amount of
refrigerant until sight glass just clears.
4. Adjust the control.
5. Open the water valve.
6. Reset or replace valve.
7. Check, replace or repair set screw (pulley), fan
motor, or inoperative fan control.
8. Clean condenser surfaces with brush and/or
vacuum.
9. Check and readjust.
10. Check contactor, thermal overload relay, check
motor, check capacitor. (If single phase)
11. Reverse two fan motor leads. (3 phase only)
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