35
No. Symptom LED
indication Abnormal point/
Condition
Condition Remedy
16
Outdoor unit
operates.
1-time
fl
ash
2.5 seconds OFF
Frequency drop by
current protection
FH06/09/12
When the input current exceeds approximately
10A (
FH06/09
)/10.5A (
FH12
), compressor fre-
quency lowers.
The unit is normal, but check the
following.
• Check if indoor
fi
lters are clogged.
• Check if refrigerant is short.
• Check if indoor/outdoor unit air
circulation is short cycled.
FH15/18
Current from power outlet is nearing breaker ca-
pacity.
17
3-time
fl
ash
2.5 seconds OFF
Frequency drop by
high pressure pro-
tection
Temperature of indoor coil thermistor exceeds 131 °F (55°C)
in HEAT mode, compressor frequency lowers.
Frequency drop by
defrosting in COOL
mode
Indoor coil thermistor reads 46°F (8°C) or less in COOL mode,
compressor frequency lowers.
18
4-time
fl
ash
2.5 seconds OFF
Frequency drop by
discharge tempera-
ture protection
Temperature of discharge temperature thermistor exceeds
232°F (111°C), compressor frequency lowers.
• Check refrigerant circuit and refrig-
erant amount.
• Refer to 10-5. "Check of LEV".
• Refer to 10-5. "Check of outdoor
thermistors".
19
MUZ-FH06/09/12
5-time
fl
ash
2.5 seconds OFF
Outside temperature
thermistor protec-
tion
When the outside temperature thermistor shorts or opens,
protective operation without that thermistor is performed.
• Refer to 10-5. Check of outdoor
thermistors.
20
Outdoor unit
operates.
7-time
fl
ash
2.5 seconds OFF
Low discharge tem-
perature protection
Temperature of discharge temperature thermistor has been
122°F (50°C) or less for 20 minutes.
• Refer to 10-5. "Check of LEV".
• Check refrigerant circuit and refrig-
erant amount.
21
8-time
fl
ash
2.5 seconds OFF
MUZ-FH06/09/12
PAM protection
PAM: Pulse Ampli-
tude Modulation
The overcurrent
fl
ows into PFC (Power factor correction
:IC820) or the DC voltage reaches 394 V or more, PAM stops
and restarts.
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.
MUZ-FH15/18
Zero cross detecting
circuit
Zero cross signal cannot be detected.
• 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".
22
9-time
fl
ash
2.5 seconds OFF
Inverter check mode The connector of compressor is disconnected, inverter check
mode starts.
• Check if the connector of the com-
pressor is correctly connected.
Refer to 10-5. "How to check
inverter/compressor".
NOTE:
1. The location of LED is illustrated at the right
fi
gure. Refer to 10-6.1.
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
OFF
2.5-second OFF
2.5-second OFF
0.5-second ON
0.5-second ON
LED
Flashing
→
MUZ-FH06/09/12
Inverter P.C. board
MUZ-FH15/18
LED
→
Flashing
OBH684C
