Mitsubishi Electric MUZ-FS06NA Service Manual page 31

No. Symptom LED indication
Outdoor unit 1-time blink
operates. 2.5 seconds OFF
16
3-time blink
2.5 seconds OFF
17
4-time blink
2.5 seconds OFF
18
MUZ-FS06/09/12
5-time blink
19
2.5 seconds OFF
Outdoor unit 7-time blink
operates. 2.5 seconds OFF
20
8-time blink
2.5 seconds OFF
21
9-time blink
2.5 seconds OFF
22
NOTE: 1. The location of LED is illustrated at the right figure. Refer to 10-6.1.
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
OBH873
Abnormal point/
Condition
FS06/09/12 When the input current exceeds approximately
Frequency drop by
current protection
FS15/18
Frequency drop by Temperature of indoor coil thermistor exceeds 131 °F (55°C)
high pressure pro- in HEAT mode, compressor frequency lowers.
tection
Frequency drop by Indoor coil thermistor reads 46°F (8°C) or less in COOL mode,
defrosting in COOL compressor frequency lowers.
mode
Frequency drop by Temperature of discharge temperature thermistor exceeds
discharge tempera- 232°F (111°C), compressor frequency lowers.
ture protection
Outside temperature When the outside temperature thermistor shorts or opens,
thermistor protec- protective operation without that thermistor is performed.
tion
Low discharge tem- Temperature of discharge temperature thermistor has been
perature protection 122°F (50°C) or less for 20 minutes.
MUZ-FS06/09/12 The overcurrent flows 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-FS15/18 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
10A (FS06/09)/10.5A (FS12), compressor fre-
quency lowers.
Current from power outlet is nearing breaker ca-
pacity.
0.5-second ON
31
Remedy
The unit is normal, but check the
following.
• Check if indoor filters are clogged.
• Check if refrigerant is short.
• Check if indoor/outdoor unit air
circulation is short cycled.
• Check refrigerant circuit and refrig-
erant amount.
• Refer to 10-5. "Check of LEV".
• Refer to 10-5. "Check of outdoor
thermistors".
• Refer to 10-5. Check of outdoor
thermistors.
• Refer to 10-5. "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 10-5. "Check of power
supply".
• Check if the connector of the com-
pressor is correctly connected.
Refer to 10-5. "How to check
inverter/compressor".
Inverter P.C. board
MUZ-FS06/09/12
Blinking →
LED
MUZ-FS15/18
Blinking
→
LED