Mitsubishi Electric MUZ-LN35VGHZ Service Manual page 43

No. Symptom LED indication
Outdoor unit 7-time blink
operates. 2.5 seconds OFF
21
8-time blink
2.5 seconds OFF
22
9-time blink
2.5 seconds OFF
23
NOTE: 1. The location of LED is illustrated at the right figure. Refer to 12-6.1.
2. LED is lit during normal operation.
The blinking frequency shows the number of times the LED blinks after every 2.5-second OFF.
(Example) When the blinking frequency is "2".
ON
2.5-second OFF
OFF
OBH768B
Abnormal point/ Con-
dition
Low discharge tem- Temperature of discharge temperature thermistor has been
perature protection 50°C or less for 20 minutes.
The overcurrent flows into PFC (Power factor correction:
MUZ-LN25/35
IC820) or the bus-bar voltage reaches 394 V or more, PAM
PAM protection
stops and restarts.
PAM: Pulse Ampli-
tude Modulation
MUZ-LN50 Zero cross signal cannot be detected.
Zero cross detecting
circuit
Inverter check mode The connector of compressor is disconnected, inverter check
mode starts.
0.5-second ON
2.5-second OFF
Condition
0.5-second ON
43
Remedy
• Refer to 12-5. "Check of LEV".
• Check refrigerant circuit and refrig-
erant amount.
This is not malfunction. PAM pro-
tection will be activated in the fol-
lowing cases:
1 Instantaneous power voltage
drop. (Short time power failure)
2 When the power supply voltage
is high.
• It occurs with following cases.
1 Instantaneous power voltage
drop. (Short time power failure)
2 Distortion of primary voltage
• Refer to 12-5. "Check of power
supply".
• Check if the connector of the com-
pressor is correctly connected.
Refer to 12-5. "How to check
inverter/compressor".
Inverter P.C. board
MUZ-LN25/35VGHZ
Blinking →
LED
MUZ-LN50VGHZ
Blinking
→
LED