Mitsubishi Electric MUZ-FH25VEHZ Service Manual page 31

No. Symptom LED indication
Outdoor unit 7-time fl ash
operates. 2.5 seconds OFF
19
8-time fl ash
2.5 seconds OFF
20
9-time fl ash
2.5 seconds OFF
21
NOTE: 1. The location of LED is illustrated at the right fi gure. Refer to 11-6.1.
2. LED is lighted during normal operation.
The fl ashing frequency shows the number of times the LED blinks after every 2.5-second OFF.
(Example) When the fl ashing frequency is "2".
ON
2.5-second OFF
OFF
OBH625A
Abnormal point/
Condition
Low discharge tem- Temperature of discharge temperature thermistor has been
perature protection 50°C or less for 20 minutes.
MUZ-FH25/35 The overcurrent fl ows into PFC (Power factor correction :
PAM protection IC820) or the bus-bar voltage reaches 394 V or more, PAM
PAM: Pulse Ampli- stops and restarts.
tude Modulation
MUZ-FH50 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
31
Remedy
• Refer to 11-5. "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 11-5. "Check of power
supply".
• Check if the connector of the com-
pressor is correctly connected.
Refer to 11-5. "How to check
inverter/compressor".
Inverter P.C. board
MUZ-FH25/35VEHZ
Flashing →
LED
MUZ-FH50VEHZ
Flashing
→
LED