Mitsubishi Electric PUH-P8MYA Technical & Service Manual page 45

<Abnormality detected during unit operation: Outdoor unit>
Abnormal- Meaning of abnormality display and
ity display abnormality troubleshooting
Discharge temperature abnormal
When the discharge thermistor tem-
perature (TH2) exceeds 118 °C while
the compressor is operating, an ab-
normality is recognized.
U2
49C trip (CN23 connector discon-
nected)
When connector CN23 opens while
the compressor is operating, an ab-
normality is recognized.
Discharge temp thermistor (TH2)
open or shorted.
When an open (0 °C or lower) or
short (216 °C or higher) is detected
while the compressor is operating, an
U3
abnormality is recognized.
(Detection is disabled for 5 minutes
at compressor starting.)
Liquid temp thermistor (TH1) or
condenser/evaporater temp ther-
mistor (TH3) open or shorted.
When an open (–39 °C or lower) or
short (88 °C or higher) is detected
while the compressor is operating, an
U4
abnormality is recognized. (Detection
is disabled for 7 minutes beginning
from 10 seconds after the compres-
sor starts and for 10 minutes after
return from defrosting.)
Compressor overcurrent trip
When the current value reaches the
overload set value or higher while the
compressor is operating, an abnor-
mality is recognized.
U6
P8MYA .................................. 22 A
P10MYA ................................ 27 A
High pressure abnormal (63H1
trip)
Detected (3.3 +0
-0.15
while compressor is operating.
UE
63H1: Pressure switch (high pres-
sure)
OFF: 3.3 MPa
(1) Compressor overheating due to insuf-
ficient refrigerant.
(2) Thermistor faulty. (TH2)
(3) Outdoor controller board faulty.
(1) Shorting connector CN23 on outdoor
controller board dislodged or contact
faulty.
(1) Connector (CN3) dislodged or con-
nect faulty.
(2) Thermistor faulty.
(3) Outdoor controller board faulty.
(1) Connector (TH1: CN2, TH3: CN4) dis-
lodged or contact faulty.
(2) Thermistor faulty.
(3) Outdoor controller board faulty.
(1) Overload operation exceeding unit us-
age range limit.
(2) Power supply terminal voltage low.
(3) Power supply missing phase.
(4) Compressor motor faulty.
(5) Compressor locked.
(6) Connector (CN22) on outdoor control-
ler board dislodged or contact faulty.
(7) 51C disconnected or contact faulty.
(1) Started with ball valve closed.
(2) Connector (CN21) on outdoor control-
MPa) by 63H1 trip ler board dislodged or contact faulty.
(3) 63H1 disconnected or contact faulty.
(4) Indoor filter clogged. Power reset de-
tected during heating overload opera-
tion (Heating).
(5) Low indoor unit air flow (heating).
(6) Low outdoor unit air flow (cooling).
(7) Part faulty.
Cause
(1) Check input super heat.
(2)(3)
(1) Repair shorting connector.
(1) Check connector contact and ther-
(2) Check thermistor resistance value, or
(3) Replace outdoor controller board.
(1) Check connector contact and ther-
(2) Check thermistor resistance value or
(3) Replace outdoor controller board.
(1) Check usage conditions.
(2) Check power supply voltage.
(3) Check wiring for breaks and faulty con-
(4) Check motor winding resistance (See
(5) Replace compressor.
(6)(7)
(1) Check if ball valve is fully open.
(2)(3)
(4) Check indoor filter.
(5) Check flow duct static pressure and for
(6) Check for faulty outdoor fan motor.
(7) Replace pressure switch.
–43–
Judgment method and remedy
Check for refrigerant leakage and
check piping length.
Charge with additional refrigerant.
Turn off power and restart operation
and check if U3 is displayed within 8
minutes.
When U3 is displayed, carry out U3 pro-
cessing.
(Do not replace board at U2 display
only.)
mistor wire.
check temperature by microcomputer.
(Check using SW2 self-diagnosis func-
tion.)
See page 36.
(Replace board after sufficiently check-
ing 1 and 2.)
mistor wire.
check temperature by microcomputer.
(Check using SW2 self-diagnosis func-
tion.)
See to page 36.
(Replace board after sufficiently check-
ing 1 and 2)
(Check for short cycle operation.)
tact.
page 35.)
After checking connections, restart and
check operation.
Repair connector.
faulty fan motor.