Panasonic U-72MF2U9 Service Manual page 170

3. 3WAY Alarm Codes
E16 Alarm
Alarm code
Alarm meaning
Alarm conditions
Probable cause
Check
Correction
Example
Notes
1
E20 Alarm
Alarm code
2
Alarm meaning
Alarm conditions
Probable cause
Check
3
Correction
Example
Notes
4
5
6
E24 Alarm
Alarm code
Alarm meaning
7
Alarm conditions
Probable cause
Check
8
Correction
Example
Notes
9
E16
More indoor units are found in Auto Addressing than the setting on outdoor PCB.
• The number of indoor units was too many when auto address setting was performed.
• After initial communications were completed, an unrecognized unit was detected.
(1) The number of indoor units set at the indoor unit quantity setting SW (SW3, SW4) on the
outdoor unit PCB is less than the number set.
(2) The inter-unit control wiring is wired incorrectly.
(1) See the section "6. TEST RUN" and check the number of indoor units that is set.
(2) Check the inter-unit control wiring at the indoor and outdoor units.
After correcting the indoor unit quantity setting or the inter-unit control wiring, perform auto
address setting again.
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E20
No indoor unit responded in Auto Addressing.
When auto address setting was performed, no indoor units were recognized.
(1) The inter-unit control wiring from the outdoor unit to the indoor units has been cut.
(2) Serial connector 1 (CN76) is disconnected at the outdoor unit.
(3) The power is OFF at all indoor units in the system.
(1) Check whether the inter-unit control wiring from the outdoor unit to the indoor units is cut.
(2) Check whether serial connector 1 (CN76) is disconnected at the outdoor unit.
(3) Check the power at the indoor units.
(1) Reconnect the inter-unit control wire from the outdoor unit to the indoor unit.
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Position of serial connector CN76 on 3WAY
OC
CN76
E24
No response from sub outdoor unit.
After initial communications were completed, communications from an outdoor unit stopped.
(1) After initial communications were completed, the control wiring between main and sub
outdoor units was disconnected.
(2) After initial communications were completed, the outdoor unit power was turned OFF.
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3WAY VRF SYSTEM
Trouble Diagnosis