Panasonic U-8ME1E81 Service Manual page 169

4. 2WAY Alarm Codes
P20 Alarm
Alarm code P20
Alarm meaning High load alarm
Alarm conditions The high pressure increase is not rapid but the alarm occurs when the horsepower down does
not meet the anticipated time.
Probable cause (1) Forgot to open the valve.
(2) Operation failure of mechanical valve
(3) Idle away of outdoor fan
Check Check the valve, mechanical valve and outdoor fan.
Correction —
Example —
Notes —
P22 Alarm
Alarm code P22
Alarm meaning Fan motor trouble
Alarm conditions Fan motor start failure, fan motor Hall IC input failure
Probable cause Possible causes are a Hall IC input circuit failure and a fan HIC failure.
Check Check the fan motor wiring, the Hall IC wiring, and the connector connections.
If the wiring and connectors are normal, then check that the capacitor of the Hall IC input circuit
is securely soldered on the outdoor unit control PCB. Also use a tester and measure the
resistance between fan HIC power (HIC+) and ground (HIC–).
If there is a short-circuit, there is an HIC malfunction.
HIC PCB for 8HP to 16HP
(A747038)
HIC PCB for 18HP and 20HP
(A747036)
Correction If the fan does not start, the below corrections may be effective.
(1) If there is a fan HIC failure or circuit failure, replace the PCB.
(2) If the fan motor is locked, replace the fan motor.
Example —
Notes Turn OFF the power, and check the continuity of "+" and "–" on the fan circuit PCB.
HIC -
(NV)
HIC +
(P)
HIC -
(NV)
HIC +
(P)
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2WAY SYSTEM
Trouble Diagnosis
6