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This troubleshooting guide is not a comprehensive analysis of the Scroll compressor refrigeration system. The aim is
to give operators simple instructions on basic unit processes so that they have the technical knowledge to identify and
bring defective operations to the notice of qualified technicians.
Problems Symptoms
Sound power levels
(A)
Compressor does not start up
Compressor terminals are live but
Discharge
motor does not start
Measurement conditions:
Contactor motor no operational
Measurements taken in a room adjacent to the room containing the FWD, at the outlet of the rectangular duct (1.5 m
long) fixed to its discharge opening.
No current ahead of motor
Fan
contactor
Unit
speed
1
FWD 08
2
Current ahead of fuse, but not on
3
contactor side
1
FWD 10
2
Low Voltage reading on
3
1
voltameter
FWD 12
2
3
1
Starter coil not excited
FWD 14
2
3
1
Compressor does not run.
FWD 20
2
Compressor motor "groans"
3
High pressure switch tripped to
contacts open on high pressure.
Intake
Discharger pressure too high
Measurement conditions:
(B)
Compressor stops - Low Pressure switch tripped
Measurements taken at the horizontal air intake.
Low refrigerant temperature or
Fan
low refrigerant pressure cut out
Unit
speed
1
Anti-freeze security tripped
FWD 08
2
3
1
Compressor stops High
FWD 10
2
Pressure switch tripped
3
1
FWD 12
2
3
1
Over current thermal relay tripped
FWD 14
2
Motor temperature thermostat
3
tripped
1
Anti-freeze security tripped
FWD 20
2
3
(C)
Compressor stops just after its start
Suction pressure too low.
Filter drier iced up
(D)
The compressor keeps running without stopping
Temperature too high in areas
requiring air-conditioning
Chilled water temperature output
too high
CG-SVX027D-GB
UNT-PRC002-GB
Problem causes
Motor burned out
Coil burned out or broken
contactors
(a) Power cut
Power level in dB(A), per Hz frequency band
(b) Main power supply switched off
125
250
500
55
50
42
57
54
47
58
57
50
Fuse blown
57
51
45
58
54
48
60
58
50
Voltage too low
57
51
45
58
54
48
60
58
50
56
62
50
Regulation circuit open
61
66
55
63
69
58
57
63
51
61
66
55
Compressor sticking (damaged or
63
69
58
sticking components)
Discharge pressure too high
Discharge pressure too high.
Power level in dB(A), per Hz frequency band
Notenoughcoolingfluid.Water
125
250
500
56
55
55
flowtoevaporatortoolow
63
62
60
66
65
63
62
58
55
66
63
60
70
67
63
62
58
55
Discharge pressure too high.
66
63
60
(a) Voltage too low
70
67
63
66
65
65
(b) Cooling demand too high, or
73
72
69
condensing temperature too
78
76
73
high.
68
72
64
(c) N otenoughcoolingfluid.
76
76
68
78
79
71
Waterflowtoevaporatortoo
low
Filter drier clogged
Excess load on cooling system
Excess cooling demand on system
Troubleshooting Guide
Action Recommended
Replace compressor
Replace contactor
Check fuses and connection. See
why system tripped. If system is
operational, switch on main power
1000
2000
4000
supply
37
37
31
40
30
38
Check motor insulation. Replace
42
32
40
42
34
fuse
33
45
38
39
48
40
42
Contact Power Supply Utility
42
34
33
45
38
39
Locate regulation device which
48
40
42
48
39
38
has tripped out and see why. See
53
47
46
instructions concerning this device
56
50
50
49
40
39
53
47
46
56
50
50
See instructions for "discharge
pressure high"
See instructions for "Low
refrigerant pressure cut out"
Repair leak. Add refrigerant.Check
1000
2000
4000
53
46
45
waterflowrate,andflowswitch
60
53
53
contact in water
62
56
55
58
51
48
62
56
55
65
59
59
58
51
48
62
56
55
See instructions for "discharge
65
59
59
65
57
50
temperature high"
71
64
59
(a) Contact Power Supply Utility
75
69
64
(b) Repair leak. Add refrigerant.
64
56
52
Checkwaterflowrate,and
71
65
61
74
69
66
flowswitchcontactinwater
Replacefilterdrier
Check thermal insulation and
air-tightness of areas requiring
air-conditioning
Check thermal insulation and
air-tightness of areas requiring
air-conditioning
Overall power
8000
dB(A)
30
46
40
50
43
53
28
48
35
51
39
54
28
48
35
51
39
54
36
56
45
60
49
63
37
57
45
60
49
63
Overall power
8000
dB(A)
42
57
53
64
57
67
44
61
52
66
57
69
44
61
52
66
57
69
46
68
57
74
63
78
50
69
61
75
66
78
11
51
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