Carrier 38MBRC Series - CURRENT & SPEED ISSUE DIAGNOSIS; PC 08;PC 44;PC 46;PC 49 Troubleshooting

38MBRC: Service Manual
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
28
PC 08 (Current Overload Protection) / PC 44 (Outdoor Unit Zero Speed Protection) / PC 46 (Compressor
Speed Has Been Out of Control) / PC 49 (Compressor Overcurrent Failure) Diagnosis and Solution
Description: An abnormal current rise is detected by checking the specified current detection circuit.
Recommended parts to prepare:
• Connection wires
• Rectifier
• PFC circuit or reactor
• Blocked refrigeration piping system
•Pressure switch
• Outdoor fan
• IPM module board
• Outdoor PCB
Troubleshooting and repair:
Was t
h
e protection activate
d
i
n stan
dby
?
Was the protection activated
in standby?
Yes
Yes
I
s
the c
u
rrent n
o
rm
a
l
˛
Is the current normal ˛
Yes
No
R
ep
l
ace t
h
e out
d
oor main PCB
Replace the outdoor main PCB
Is the power voltage normal ?
I
s
o
ut
d
oor termina
l
vo
l
tage
norma
l
˛
Is outdoor terminal voltage
normal˛
R
estart t
h
e unit w
h
en t
h
e power supp
l
y
r
et
u
rns t
o
n
o
rm
al
Restart the unit when the power supply
returns to normal.
No
Yes
No
o
nnect t
h
e
p
ower w
i
r
i
ng
Reconnect the
power wiring
Yes
Is the voltage between L and N normal?
Yes
Is t
h
e input voltage o
f
t
h
e
bridge recti

er
˛
Is the input voltage of the
bridge rectier normal?
No
No
Is t
h
e power wiring
wire
d
correct
l
y
?
Is the power wiring
wired correctly?
R
e
c
onnec
t
L an
d
N
Reconnect L and N
Are L an
d
N wire
d
proper
l
y
?
Are L and N wired
properly?
R
econnec
t
t
h
e
bridge recti

er
Reconnect the
bridge rectier
recti

er wired
p
roper
l
y
?
Is the bridge
rectier wired
properly?
No
No
Yes
Rep
l
ace t
h
e PFC mo
d
u
l
e
(
i
f
t
hi
s
h
a
s
n
ot
b
een
d
one a
l
rea
d
y
)
Replace the PFC module (if this has not
been done already)
No
I
s
t
h
e vo
l
tage
b
etween P an
d
N
n
o
rm
al
re
f
er according to
In
d
ex
˛
Is the voltage between P and N
normal refer according to
Index˛
b
ridge recti

er
Replace the bridge rectier
No
Is the
bridge rectier
functioning
norma
l
ly
?
I
fu
y
?
Is the bridge rectier
functioning normally?
Is
the wiring o
f
the
r
eac
t
or or
i
n
d
uctance
proper
l
y wire
d
?
I
Is the wiring of the
reactor or inductance
properly wired?
Reconnect the
wiring.
No
Are the
r
eactor and
i
n
d
uctance
f
unctioning
no
rm
a
ll
y
A
d
Are the reactor and
inductance functioning
normally
Yes
Rep
l
ace re
a
c
to
r
o
r
in
du
ct
a
nce
Replace reactor or
inductance
No
Is the outdoor ambient
temperature higher than 50 °C?
No
Stop the unit
Yes
ventilation
f
unctioning
proper
l
y
?
Is the outdoor unit
ventilation functioning
properly?
Yes
Ensure that the outdoor unit
ventilates properly.
Is t
h
e
h
eat exc
h
anger
d
irty
?
Is the heat exchanger dirty ?
No
C
l
ean t
h
e
h
eat exc
h
anger
Clean the heat exchanger
Yes
C
heck whether the re
f
rigerant
system is running norma
ll
y
Check whether the refrigerant
system is running normally
Rep
l
ace out
d
oor main
b
oar
d
.
Does a pro
bl
em sti
ll
e
xist
?
Replace outdoor main
board. Does a problem still
exist?
No
No
Is the outdoor
f
an running
proper
l
y
?
Is the outdoor fan running
properly?
Ple
a
se re
f
er t
o
the s
o
l
u
ti
o
n
of
the
"
f
an speed is operating outside o
f
the normal ran
g
e" m
a
lf
u
ncti
on
.
Please refer to the solution of the
" Fan speed is operating outside of
the normal range " malfunction.
No
Yes
No
Yes
Yes
Is system pressure too
h
ig
h
?
Is system pressure too high ?
Rec
y
cle the overcharged
r
e
fri
g
eran
t
Recycle the overcharged
refrigerant
Yes