MXZ-SM36NAMHZ Service Manual

70
OCH789
Check code
Freeze protection of Branch box or Indoor unit
Abnormal points and detection methods Causes and checkpoints
The purpose of the check code is to prevent indoor unit from freezing or
dew condensation which is caused when a refrigerant keeps owing into
the unit in STOP.
When all of the following conditions are satised:
1. The compressor is operating in COOL mode.
2. 15 minutes have passed after the startup of the compressor, or the
change in the number of operating indoor units is made (including a
change by turning thermo-ON/OFF).
3. After the condition 2 above is satised, the thermistor of indoor unit
in STOP detects TH22j
[
23°F [−5°C] for 5 consecutive minutes.
1
Wrong piping connection between indoor unit and
branch box
2
Miswiring between indoor unit and branch box
3
Miswiring of LEV in branch box
4
Malfunction of LEV in branch box
●Diagnosis of defects
Make sure to turn the power OFF before connecting/disconnecting any connectors, or replacing boards.
Diagnosis Remedy
v
1503
(P6)
Check the port which the piping and
wiring between the indoor unit and
branch box is connected.
Is the piping and wiring connected to the
same port?
Check the port which the LEV wiring of
branch box is connected.
Is the wiring connected to the same port as
the corresponding branch box?
Check the LEV wiring of indoor unit that is not
via branch box is connected properly.
Is the resistance detected?
Disconnect the LEV wiring of branch box or indoor
unit to check the resistance.
Connect the piping and wiring to the same
port.
Connect the LEV wiring to the intended
port properly.
Connect the LEV wiring properly.
Replace the LEV coil.
Replace the LEV assy in branch box or
the LEV of indoor unit that is not
via branch box.
Yes
Yes
Yes
Yes
No
No
No
No