Panasonic U-8MF2E8 Service Manual page 138

4. 3WAY Alarm Codes
H11, H12 Alarm
Alarm code
Alarm meaning
Alarm conditions
Probable cause
Check
5
Correction
Example
H11, H12
H11: Constant speed compressor 2 overcurrent alarm
H12: Constant speed compressor 2 lock current alarm
H11: During operation, when the compressor current value exceeds the following values for 30
seconds or longer listed below table.
However this alarm is not detected for 4 seconds after the compressor starts.
Horsepower of outdoor unit
Overcurrent (A)
H12: During operation, when the compressor current value exceeds the following values for 4
seconds or longer listed below table.
However this alarm is not detected for 2 seconds after the compressor starts.
Horsepower of outdoor unit
Lock current (A)
(1) Compressor failure (locked or partially locked)
(2) CT circuit failure (including cut wiring)
(3) Missing power phase
(4) Low power voltage
(5) PCB failure
(1) Compressor failure (partially locked)
Trouble: Current value during operation greatly exceeds the value shown above.
Check: When the current for each phase is measured with a clamp meter or similar instrument,
check that the current value for all phases is not high.
If MG was forced ON (use caution), check that compressor noise will not occur or
the compressor will not run with a groaning sound.
(2) CT circuit failure, PCB failure
Trouble:
Check: • Check for poor connector contact.
• Check the continuity of the CT circuit.
• Install a normal CT in place of this CT and check.
If current is detected, then the PCB can be judged OK.
CT circuit failure
• Check that current is flowing in the phase where the CT circuit is connected.
Check voltage and current.
(3) Missing power phase
Trouble: This alarm primarily occurs when the T-phase is missing.
When the R-phase or S-phase is missing, CT trouble or PCB continuity trouble occur.
However this may not be true in the case of a missing phase caused by magnet SW
trouble.
Check: There is the possiblility of a magnet SW failure.
Therefore, check the phase voltage at a location that is as close to the compressor as
possible.
(4) Low power voltage
Trouble: In most cases, this occurs when another constant-speed compressor (including
compressors in other units) or other device starts.
It also occurs when the power wiring is extremely long.
Check: Check the voltage between each of the phases.
However, if this trouble occurs when other devices or compressors start, an oscilloscope
is required.
(5) PCB failure
Trouble:
Check: Check that the current value measured with the clamp meter is not lower than the value
measured with the PC or remote controller.
(6) If the cause is still unknown after checking the above, there is possibility that noise is the cause of
the trouble. It is necessary to connect a PC or other instrument.
(1) Replace the compressor.
(2) Replace the CT circuit.
(3) Repair the power circuit.
(4) Adjust the primary-side power. Repair the power wiring.
(5) Replace the outdoor unit PCB.
(6) Correct the trouble.
* In the case of a compressor failure, it is likely that steps must be taken to correct the cause
of the compressor failure (such as liquid back-up) in order to prevent recurrence. Be sure to
check that there is no cause which may resuit in compressor locking.
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12HP 14HP 16HP
13.6 13.6 16.3
12HP 14HP 16HP
16.1 16.1 19.3
5 - 16
3WAY SYSTEM
Trouble Diagnosis