Daikin 2MXS18NMVJUA User Manual

Troubleshooting for Outdoor Unit SiUS121736EA
181 Service Diagnosis
7.2 Low-voltage Detection or Over-voltage Detection
Error Code U2
Outdoor Unit LED
Display
A j 1 i 2 h 3 h 4 i 5 h
Method of Error
Detection
 Indoor Unit
The zero-cross detection of the power supply is evaluated by the indoor unit PCB.
 Outdoor Unit
Low-voltage detection:
An abnormal voltage drop is detected by the DC voltage detection circuit.
Over-voltage detection:
An abnormal voltage rise is detected by the over-voltage detection circuit.
Error Decision
Conditions
 Indoor Unit
There is no zero-cross detection in approximately 10 seconds.
 Outdoor Unit
Low-voltage detection:
 The voltage detected by the DC voltage detection circuit is below 150 V for 0.1 second.
 If the error repeats, the system is shut down.
 Reset condition: Continuous run for about 60 minutes without any other error
Over-voltage detection:
 An over-voltage signal is fed from the over-voltage detection circuit to the microcomputer.
 The compressor stops if the error occurs, and restarts automatically after 3-minute standby.
Supposed
Causes
 Power supply voltage out of specification
 Defective DC voltage detection circuit
 Defective over-voltage detection circuit
 Defective PAM control part
 Disconnection of compressor harness
 Short circuit inside the fan motor winding
 Noise
 Momentary drop of voltage
 Momentary power failure
 Defective outdoor unit PCB
 Defective indoor unit PCB

Daikin 2MXS18NMVJUA Specifications

General

Brand	Daikin
Model	2MXS18NMVJUA
Category	Air Conditioner
Language	English