Troubleshooting by Indication on the Remote Controller ESIE09-05
212 Troubleshooting
3.41 “U4” Malfunction of Transmission between AHUs and
Outdoor Units
Remote
Controller
Display
U4
Applicable
Models
AII AHU models
ERQ 125 ~ 200 A7V1
Method of
Malfunction
Detection
Microcomputer checks if transmission between AHUs and outdoor units is normal.
Malfunction
Decision
Conditions
When transmission is not carried out normally for a certain amount of time
Supposed
Causes
Indoor to outdoor, outdoor to outdoor transmission wiring F1, F2 disconnection, short circuit
or wrong wiring
Outdoor unit power supply is OFF
System address doesn’t match
Defect of outdoor unit PC board
Defect of AHU PC board
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