Panasonic U-72MF2U9 Service Manual page 171

3. 3WAY Alarm Codes
E25 Alarm
Alarm code E25
Alarm meaning The outdoor unit address is duplicating.
Alarm conditions Communication by outdoor unit main-sub control wiring was received that contained the same
address as that unit 5 times or more within 3 minutes.
Probable cause The unit number is set incorrectly.
Check Check the unit number again.
Correction Correct the incorrect unit number setting.
Example —
Notes Recovery from this alarm occurs automatically (when communication that contains the same
address is not received for 3 minutes).
E26 Alarm
Alarm code E26
Alarm meaning The number of responding outdoor units does not match with the setting on the main outdoor unit.
Alarm conditions After power initialization, the set outdoor unit quantity did not match the number of outdoor units
detected on the outdoor unit main-sub control wiring for 3 minutes or longer.
Probable cause (1) The outdoor unit quantity is set incorrectly.
(2) The outdoor unit main-sub control wiring is disconnected.
Check (1) Check the outdoor unit quantity setting again.
(2) Check the outdoor unit main-sub control wiring.
Correction (1) Correct the incorrect outdoor unit quantity setting.
(2) Repair the outdoor unit main-sub control wiring.
Example —
Notes Recovery from this alarm occurs automatically (when the set outdoor unit quantity matches the
number of outdoor units detected on the outdoor unit main-sub control wiring).
E29 Alarm
Alarm code E29
Alarm meaning No response from main outdoor unit.
Alarm conditions Outdoor unit communications from outdoor unit (main) were interrupted for 3 minutes or longer.
Probable cause (1) After initial communications were completed, the inter-outdoor unit control wiring was cut.
(2) After initial communications were completed, the RC connector became disconnected.
(3) The power at the outdoor unit (main) is turned OFF.
Check (1) Check the inter-outdoor unit control wiring.
(2) Check the RC connectors.
(3) Check the power at the outdoor unit (main).
Correction (1) Repair the inter-outer unit control wiring.
(2) Correct the RC connector connection.
(3) Turn ON the outdoor unit (main) power.
Example —
Notes —
E31 Alarm
Alarm code E31
Alarm meaning Error in communication inside outdoor unit control box.
Alarm conditions —
Probable cause When does it occur?
(1) When failed in rewriting microcomputer.
(2) When the unit power shut down during rewriting microcomputer.
(3) When wiring between the Outdoor Unit Control PCB and ROM writer disconnected.
Check (1) Rewrite microcomputer again.
(2) Switch on the unit power again.
Correction Replace the Outdoor Unit Control PCB.
Example —
Notes —
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3WAY VRF SYSTEM
Trouble Diagnosis
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