Carrier 38MGQ Series - Low Pressure Protection Error Diagnosis (P2)

57
P2 (Low pressure protection) error diagnosis and
solution
Error Code P2
Malfunction decision conditions If the sampling voltage is not 5V, the LED displays the failure.
Supposed causes
S Wiring mistake
S Over load protector faulty
S System block
S Outdoor PCB faulty
L
ow
p
ressure protec

o
n
Low pressure protecon
Wh
et
h
er t
h
e w
i
r
i
ng
b
etween t
h
e
l
ow pressure
protector an
d
ma
i
n contro
l
b
oar
d
i
s connecte
d
we
ll
o
r
correct
ly
Whether the wiring
between the low pressure
protector and main control
board is connected well or
correctly
Method
:
Disconnect the plu
g
.
Measure the resistance o
f
the
low
p
ressure
p
rotecto
r
.
I
f
th
e
p
rotector is norma
l
t
h
e va
l
ue is
o
Method
: Disconnect the plug.
Measure the resistance of the
low pressure protector. If the
protector is normal the value is
o
Yes
Yes
C
onnect it we
ll
Connect it well
R
ep
l
ace out
d
oor ma
i
n
b
oar
d
Replace outdoor main board
No
R
ep
l
ace
l
ow pressure protector
Replace low pressure protector
No
Wh
e
th
e
r th
e
l
o
w
pressure protector
i
s
b
r
o
k
e
n
Whether the low
pressure protector
is broken
Check whether the outdoo
r
a
m
bi
ent temperature
i
s to
o
l
o
w
Check whether the outdoor
ambient temperature is too
low
No
Stop t
h
e uni
t
Stop the unit Yes
O
pen fu
ll
y va
l
ve core o
f
hi
g
h
pressure va
l
v
e
Open fully valve core of
high pressure valve
No
C
h
ec
k
w
h
et
h
er va
l
ve core
of
high
p
ress
u
re
va
l
ve is
o
pene
d
Check whether valve core
of high pressure valve is
opened
Check i
f
the indoor
f
an runs
p
roper
l
y in coo
l
ing mo
de
Check if the indoor fan runs
properly in cooling mode
please re
f
er to the solution o
f
f
an
s
peed has been out o
f
control
mal
f
unctio
n
.
F
in
d
out t
h
e cause an
d
h
ave it so
l
ve
d
.
please refer to the solution of fan
speed has been out of control
malfunction. Find out the cause and
have it solved.
No
Yes
Yes
No
Check whether the re
f
rigerant
system is o
k
Check whether the refrigerant
system is ok
R
e
f
rigerant is not enough add the
re
f
rigerant
Refrigerant is not enough add the
refrigerant
No