Panasonic CS-VZ9SKE Service Manual page 122

17.4.21 H99 (Indoor Unit Heat Exchanger Freezing Protection (Error Code is to be Stored in
the Memory only))
Troubleshooting
Check for clogged filter on the indoor unit.
Is the rotation of the indoor unit fan motor slow?
Check for bad connection of the connector of the indoor unit pipe temperature
sensor.
Check for the characteristics of the indoor unit heat exchanger temperature sensor.
Refer to the characteristic table for electronic circuit diagram.
(Remove the connector and check the resistance value of the sensor.)
No abnormality
is observed
Check for frozen indoor unit heat exchanger.
Check the gas pressure during the rated cooling operation.
Check for presence of gas leak.
Diagnosis Procedures and Cause
No abnormality is observed
No abnormality is observed
No abnormality is observed
For some models, the sensor is not connected by a connector but
it is directly soldered to the board.
In this case, replace the control board.
Frozen
Lower than the standard value
There is a gas leak
Filter is clogged
Rotation is slow
Disconnection/
Imperfect
connection of
the connector
An abnormality
is observed
Not frozen
Normal
There is no
gas leak
122
Measures to be Taken
Clean the filter.
Replace the indoor unit fan motor.
Fix the problem.
Replace the indoor unit heat
exchanger temperature sensor.
Replace the indoor unit control board.
Replace the capillary tube or
expansion valve.
Replace the part from which gas is
leaking.