Panasonic U-72MF1U9 Service Manual page 73

3. W-3WAY VRF Alarm Codes
F08
Alarm meaning Outdoor air temperature sensor (AIR TEMP) trouble
Alarm conditions (1) A/D step is 10 steps or less (short circuit).
(2) A/D step is 1014 steps or more (open circuit)
Probable cause (1) Sensor malfunction (including connector)
(2) PCB malfunction
Check (1) Measure the sensor resistance. Check that the sensor is operating normally.
(2) Use a remote controller monitor or PC monitor to check the temperature that is recognized by
the microcomputer.
Correction
Example
Notes
Alarm code F12
Alarm meaning Compressor intake temperature sensor (SCT) trouble
Alarm conditions (1) A/D step is 10 steps or less (short circuit).
(2) A/D step is 1014 steps or more (open circuit)
Probable cause (1) Sensor malfunction (including connector)
(2) PCB malfunction
Check (1) Measure the sensor resistance. Check that the sensor is operating normally.
(2) Use a remote controller monitor or PC monitor to check the temperature that is recognized by
the microcomputer.
Correction
Example
Notes
F16 Alarm
Alarm code F16
Alarm meaning High-pressure sensor trouble (abnormal rise in high pressure) (In some cases this may not be the
result of a high-pressure sensor malfunction.)
Alarm conditions High-pressure SW activated although the detected pressure was lower (3.03 MPa or below) than
the high-pressure SW activation pressure: Undershift
High-pressure SW failed to activate although the detected pressure was higher (3.43 MPa or
above) than the high-pressure SW activation pressure: Overshift
The saturation temperature at the detected pressure is 5°C or more below the highest indoor-unit
E1 temperature continuously for 30 minutes.
High-pressure sensor disconnected or open circuit.
Probable cause (1) High-pressure sensor malfunction
(2) Failure to connect the connector to the outdoor unit PCB
(3) Failure to open the service valve
(4)
Clogged tubing
(5)
Valve leakage
(6)
Over-charging
(7)
Outdoor unit PCB failure
(8)
Electrical noise
3 - 11
Trouble Diagnosis
1
2
3
4
5
Continued
6
7