Panasonic U-8MF2E8 Service Manual page 149

5. Blinking Inspection Display
Blinking inspection display (2) (compressor magnet SW seizing detection)
Alarm code (Blinking inspection display)
Alarm meaning Compressor magnet SW seizing detected
Status: Although an outdoor unit exists where the outdoor unit fan is running, no compressors in
Alarm conditions Current is detected in the CT circuit when the compressor is stopped.
(1) This control is not engaged for the first 30 seconds after the compressor turns ON
(2) For 1 minute following the first 30 seconds after the compressor turned ON
threshold for the detected current is 10 A or more continuing for 2 seconds.
(3) All times other than the above:
• If the low-pressure SW has not activated, the threshold for the detected current is 7A or
more continuing for 5 seconds.
• If the low-pressure switch has activated, the threshold for the detected current is 7A or more
continuing for 2 seconds.
Probable cause (1) Magnet SW malfunction
• The magnet SW has seized, and the compressor is continuing to run.
• The conditions of magnet SW operation are poor (difficult to open).
(2) CT circuit failure or PCB failure (A/D failure)
• CT circuit contact failure
• Current of 7A or higher was detected although the compressor was stopped, or a higher
current was detected at occasional intervals.
• The compressor continues to operate at a time when the outdoor unit should be stopped
(such as when all indoor units are stopped).
(3) Installation error
• CT1 connector is connected to the compressor 2 side
• CT1 circuit is connected to the compressor 2 side
• CT2 connector is connected to the compressor 1 side
• CT2 circuit is connected to the compressor 1 side
(4) Electrical noise
Correction (1) Replace the CT circuit.
(2) Replace the magnet SW.
(3) Replace the PCB.
If the above probable causes are not the cause of the alarm, it is possible that in rare cases
the alarm may be caused by the effects of noise. See notes.
Notes The effects of electrical noise are difficult to identify unless a PC is connected and the conditions
are monitored for a long period of time.
the system are operating.
Because the fan is running only at the outdoor unit where seizing was detected, check
the corresponding outdoor unit.
* The fan may also run on its own when fan cracking prevention control is in effect
or when snowfall sensor input is present. Therefore monitor for approximately 10
minutes if the outdoor unit fans are operating at multiple units.
Even when the power is turned OFF, the primary side and secondary side contacts
remain together.
When a magnet SW is used in a DC circuit, it may be difficult for the SW to open at times.
In an AC circuit the magnet SW should open instantaneously as long as the current is
within the allowable range. However, this kind of trouble can occur if excessive current
flows, and may prevent the SW from opening.
Check that the connector is not partially disconnected.
Wiggle the connector to check the connection.*
* These symptoms will not occur if the connector is completely disconnected or the wire is
cut. In these cases alarm Hx3 occurs.
Check whether or not 200 - 240 V is output from the PCB to the magnet SW. If the voltage
is output, there is a PCB failure.
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3WAY SYSTEM
Trouble Diagnosis
OFF.
OFF, the
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