46
Outdoor thermistor abnormality
MXZ-32NV
Disconnect the connectors CN661, CN662 and CN663 from the outdoor controller.
(Check the characteristic of thermistors.)
F Checking the outdoor thermistors
(Simple check method for main components)
Measure the resis-
tance between
pin3 and pin4 at
CN641(MXZ-18NV)
pin1 and pin2 at
CN661(MXZ-32NV)
As per the Chara-
cteristic Chart?
(See page 49, 51 .)
2 Disconnect the compressor lead wire.
Turn on POWER to the
indoor and outdoor unit
Defrost
Thermistor
Yes
No
Yes
No
No
No
Is there voltage of
2.5 to 4.0V DC between
terminals of R681 and R682 ?
Gas pipe temperatore thermistor
Discharge
thermistor
Outdoor controller
board defective
Disconnect the
connector
(Poor connection.)
Measure the
voltage between
terminals on the
outdoor controller
board.
Is there voltage of
0.3 to 0.6VDC across
R685(MXZ-18NV),
R652(MXZ-32NV) at
11
;
to 36
;
of
outside temperature?
Is there voltage of 2.5
to 4.0V DC across
R641(MXZ-18NV),
R642(MXZ-32NV)?
As per the Chara-
cteristic Chart?
(See page 49, 51 .)
As per the Chara-
cteristic Chart?
(See page 49, 51 .)
As per the Chara-
cteristic Chart?
(See page 49, 51 .)
Thermistor damaged
No
Yes
No
Yes
Thermistor damaged
No
No
Yes
Yes
Measure the resis-
tance between
pin3 and pin4 at
CN661(MXZ-18NV)
pin1 and pin2 at
CN661(MXZ-32NV).
Measure the resis-
tance between
pin1and pin2, 3
and 4, 5 and 6, and
at CN662 respec-
tively (MXZ-18NV)
pin1 and pin2 at
CN661 (MXZ-32NV).
Measure the resis-
tance between pins
5 and 6 at CN661,
and pins 7 and 8
at CN662 respec-
tively (MXZ-18NV)
pin1 and pin2 at
CN661 (MXZ-32NV).
Defrost
thermistor
Discharge
temperature
thermistor
Gas pipe
temperature
thermistor
Suction
Evaporation
temperature
thermistors
Fin
temperature
thermistor
Measure the
resistance
between pin1
and pin2 at
CN663 (MXZ-18NV)
pin1 and pin2 at
CN661 (MXZ-32NV).
Yes
Yes
Evaporator/ suction
temperature thermistor.
1 Connect the connections CN661, CN681, CN682, CN683
CN641 (MXZ-18NV),CN661, CN662, and CN663 (MXZ-32NV).
Is there voltage of
0.8 to 2.5V DC between
terminals of R661 ?
Fin temperature thermistor.
Is there voltage of
2.5 to 4.0V DC between
terminals of R683 and R684 ?
Cooling operation works when heating is expected.
• First, measure the resistance of the reversing valve coil to check the integrity.
• If connector CN61(MXZ-18NV), CN913(MXZ-32NV) is not connected or the reversing valve coil is open, voltage
occurs between terminals even when the control is OFF.
G Checking the reversing valve coil
Disconnect the lead wire
between compressor and
IPM board.
Three minutes after
power-on. Check the
voltage between pin1
and pin2 at CN913 on
the noise filter board.
Is there voltage of 220 to
240V AC ?
• Reversing valve coil
lead wire defective.
• Poor contact of
connector.
• Reversing valve coil
damaged.
Outdoor controller board
or noise electronic control
P.C. board detective.
Turn on power to the indoor
unit and the outdoor unit,
and press the emergency
switch for heating operation.
No
Yes
Three minutes after
power-on. Check the
voltage between pin1
and pin2 at CN61 on
the electronic control
P.C. board. Is there
voltage of 220 to 240V AC?
Outdoor controller board
or noise filter board
detective.
No
Yes
MXZ-32NV
MXZ-18NV
MXZ-18NV
Disconnect the connectors CN641, CN661 and CN681,CN682,CN683 from the outdoor controller.
