Mitsubishi Electric PRH-P8MYA Technical & Service Manual page 65

Abnormal- Meaning of abnormality display and
ity display abnormality troubleshooting
UE
Low Pressure Abnormality (63L
operation)
Considered abnormal when 63L
goes into operation during compres-
sor operation (0±0.02MPa or above)
63L:Pressure switch (Low Pres-
sure)
OFF:0±0.02(MPa)
ON :0.06±0.04(MPa)
UL
Cause
(8) Fan motor lock on the outdoor-side
(9) Fan motor malfunction on the outdoor
-side
(10) Short cycle on the outdoor-side
(11) Dirty heat exchanger on the outdoor
-side
(12) Reduced air flow on the outdoor-side
due to dirty fan
(13) Disconnected connector (63H1) on
the outdoor-side controller board or
contact failure
(14) Disconnected 63H1 or contact failure
(15) Controller board failure on the out-
door-side
(16) LEV malfunction
(Fully closed due to disconnected
wiring)
(17) Defective parts
(18) Drop in power supply voltage
(19) 52C failure
(1) Instantaneous vacuum state due to
uneven distribution of refrigerant im-
mediately after refrigerant charging
(insufficient refrigerant in the low
pressure line)
(2) Gas leak or insufficient gas
(3) Fully closed LEV due to disconnected
wiring or locking
(4) Short cycle on the indoor-side
(5) Clogged filter on the indoor-side
(6) Reduced air flow on the indoor-side
due to dirty fan
(7) Dirty heat exchanger on the indoor-
side
(8) Fan motor lock on the indoor-side,
motor malfunction
(4)~(8) Drop in low pressure due to
reduced evaporation capacity during
cooling
(9) Short cycle on the outdoor-side
(10) Dirty heat exchanger on the outdoor-
side
(11) Fan motor lock, motor malfunction, or
FANCON board malfunction on the
outdoor-side
(9)~(11) Drop in low pressure due to
reduced evaporation capacity during
heating operation
(12) Disconnected connector (63L) on the
outdoor-side controller board or con-
tact failure
(13) Disconnected 63L or contact failure
(14) Defective controller board on the out-
door-side
(15) Defective parts
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Judgment method and remedy
(8)~(12):During cooling operation
Check the unit on the outdoor-side,
and correct the problems.
(13)(14):Check the connectors
Turn off the power, and make sure F2
is displayed when the power is turned
back on.
When F2 is displayed, follow the reme-
dy for F2.
(15) Replace the controller board on the
outdoor-side
(16) Check the LEV.
Refer to page 55.
(17) Replace high-pressure pressure
switch
(18) Check the input voltage at the power
supply terminal (TB1).
(19) Make sure 52C is operating normally.
Once the low-pressure pressure error is
experienced, do not restart the unit by
power reset before taking the following
steps (Otherwise, the compressor will be
damaged.)
<Trouble Assessment>
Check for a clogged piping.
Refer to the section on troubleshooting
the LEV (p.55).
<Remedy>
After confirming that the piping is not
clogged, perform an error reset by
power reset.
Run a 10 to 15 minutes of operation in
the mode opposite to the mode in
which the protection function tripped
(Run a hating operation if the problem
happened in the cooling mode, or vice
versa.)
Follow the same procedure if no clog-
ging in the piping was found.
(1) Restart and check the operation after
performing an error reset.
(2) Check the refrigerant amount.
(3) Run a cooling or a heating operation
and check the operating conditions.
Refer to the section on Trouble shoot-
ing the LEV.
(4)~(8):During cooling operation
Check the unit on the indoor-side, and
correct the problems.
(9)(10):During heating operation
Check the unit on the indoor-side, and
correct the problems.
(11) Check the fan on the outdoor-side
Refer to the section on Trouble shoot-
ing the Outdoor Unit Fan
(12)(13)Check the connectors
(14) Replace controller board on the out-
door-side
(15) Replace low-pressure pressure switch