Service manual
5-3
T-294-01
CONDITION
POSSIBLE CAUSE
REMEDY/
REFERENCE
SECTION
5.7 ABNORMAL PRESSURES (COOLING)
Condenser coil dirty 6.18
Condenser fan rotating backwards 6.19
Condenser fan inoperative 6.19
High discharge pressure
Refrigerant overcharge or noncondensibles 6.7
H
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Discharge pressure regulator valve defective Replace
Perishable set point Normal
Stepper motor suction modulation valve (SMV) malfunction 6.24
Filter-drier partially plugged 6.12
Low refrigerant charge 6.5/6.7
Expansion valve defective 6.25
L
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No evaporator air flow or restricted air flow 5.10
L
ow suct
i
on pressure
Excessive frost on evaporator coil 6.15/6.17
Evaporator fan(s) rotating backwards 6.15/6.17
Discharge pressure regulator valve defective Replace
Stepper motor suction modulation valve (SMV) malfunction 6.24
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Heat exchanger defective Replace
S
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d
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c
h
a
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p
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tend to equalize when unit is
Compressor valves defective 6.9
q
operating
Compressor cycling/stopped Check
5.8 ABNORMAL NOISE OR VIBRATIONS
Loose mounting bolts T ighten
C
o
m
p
r
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s
s
o
r
Worn bearings 6.8
C
ompressor
Worn or broken valves 6.8
Liquid slugging 5.11
Bent, loose or striking venturi Check
Condenser or Evaporator Fan
Worn motor bearings 6.16/6.19
C
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E
v
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F
a
n
Bent motor shaft 6.16/6.19
5.9 TEMPERATURE CONTROLLER MALFUNCTION
Defective Sensor 6.23
Defective wiring Check
Will not control
Fuse (F1, F2) blown Replace
Stepper motor suction modulation valve (SMV) circuit
malfunction
6.24
5.10 NO EVAPORATOR AIR FLOW OR RESTRICTED AIR FLOW
E
v
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p
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t
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c
o
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b
l
o
c
k
e
d
Frost on coil 5.6
E
vaporator co
i
l
b
l
oc
k
e
d
Dirty coil 6.14
Evaporator fan motor internal protector (IP) open 6.16
N
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w
Evaporator fan motor(s) (EM) defective 6.16/6.17
N
o or part
i
a
l
evaporator a
i
r
f
l
ow
Evaporator fan(s) loose or defective 6.16
Evaporator fan contactor (EF or ES) defective Replace