Mitsubishi Electric PUH-P8MYA Technical & Service Manual page 48

<Abnormality detected during unit operation: Indoor unit>
Abnormal- Meaning of abnormality display and
ity display abnormality troubleshooting
Drain overflow protection opera-
tion
1) When the drain sensor thermistor
overheats and the temperature
rise is small, the compressor en-
ters the check mode and is turned
off and the indoor fan is turned off.
2) If the state above is detected again
in the check mode, drain pump
abnormality is recognized.
3) Always detected during drain
pump operation.
Water leakage abnormality (PDH
P5
only)
1) When the drain sensor thermistor
overheats and the temperature
rise is small, the compressor en-
ters the check mode and the drain
pump is turned on for 6 minutes.
(Detection: 1 time/hour)
2) If the state above is detected
again within 12 hours after the
check mode was entered, a wa-
ter leakage abnormality is recog-
nized.
3) Detected during stop, fan, and
heat operation.
Freezing/excessive rise protection
operation
1) Freezing protection
When the piping temperature re-
mains at –15 °C or lower for 3 min-
utes after 3 minutes have elapsed
since the compressor started, the
compressor enters the 6 minutes
restart prohibit mode and if the
piping temperature again remains
at –15 °C for 3 minutes within 16
minutes after 6 minutes restarting,
P6
an abnormality is recognized.
2) Excessive rise protection
When a piping temperature rise
to 70 °C or higher is detected af-
ter the compressor starts, the
compressor enters the 6 minutes
restart prohibit mode. If a piping
temperature rise up to 70 °C or
higher is detected again within 10
minutes after 6 minutes restarting,
an abnormality is recognized.
Cause
(1) Drain pump trouble.
(2) Drain faulty.
Drain pump clogged.
Drain pipe clogged.
(3) Water droplets on drain sensor.
Drain water waves created by trans-
mission of drain water from lead wire,
clogged filter, etc.
(4) Indoor controller board faulty.
(1) Water leaking from humidifier water
supply pipe.
(2) Water droplets on drain sensor.
(3) Indoor controller board faulty.
<Cool and dry>
(1) Filter is clogged (insufficient air flow).
(2) Air duct short cycle.
(3) Low load operation (low temperature)
exceeding allowable range.
(4) Indoor fan motor faulty.
(5) Outdoor fan control faulty (intermedi-
ate period, winter).
(6) Refrigerant overcharged.
(7) Refrigerant circuit faulty (clogged).
<Heat>
(1) Filter clogged (insufficient air flow)
(2) Air duct short cycle.
(3) Overload operation (high tempera-
ture) exceeding allowable range.
(4) Indoor fan motor faulty.
(5) Outdoor fan control faulty (intermedi-
ate period)
(6) Refrigerant overcharged.
(7) Refrigerant circuit faulty (clogged)
(8) Outdoor unit bypass circuit faulty.
–46–
Judgment method and remedy
(1) Check drain up mechanism.
(2) Check drain characteristic.
(3) Check drain sensor lead wire arrange-
ment and check for filter clogging.
(4) If abnormality reproduced by shorting
between drain sensor connector CN31
pins 1 and 2 and operating air condi-
tioner, replace indoor controller board.
If there are no problems above, there
are no abnormalities.
Turn on the power and operate.
(1) Repair water leakage.
(2) Check drain sensor lead wire arrange-
ment and check for filter clogging.
(3) If abnormality reproduced by shorting
between drain sensor connector CN31
pins 1 and 2 and operating air condi-
tioner, replace indoor controller board.
If there are no problems above, there
are no abnormalities.
Turn on power and operate.
<Cool and dry>
(1) Check filter for clogging.
(2) Remove obstruction.
(4) Check fan motor operation and wind-
ing resistance.
(5) Check outdoor fan motor operation.
(6)(7)
Check refrigerant circuit operation.
<Heat>
(1) Check filter for clogging.
(2) Remove obstruction.
(4) Check fan motor operation and wind-
ing resistance.
(5) Check outdoor fan motor operation.
(6)-(8)
Check refrigerant circuit operation.