Mitsubishi Electric MUZ-GE25VA-a1 Service Manual page 70

11-3. TROUBLESHOOTING CHECK TABLE
No. Symptom LED indication
Outdoor unit 1-time fl ash
16
operates. 2.5 seconds OFF
3-time fl ash
2.5 seconds OFF
17
4-time fl ash
2.5 seconds OFF
18
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
OBH532E
Abnormal point/
Condition
Frequency drop by Current from power outlet is nearing breaker capacity.
current protection
Frequency drop by Temperature of indoor coil thermistor exceeds 55°C in HEAT
high pressure pro- mode, compressor frequency lowers.
tection
Frequency drop by Indoor coil thermistor reads 8°C or less in COOL mode, com-
defrosting in COOL pressor frequency lowers.
mode
Frequency drop by Temperature of discharge temperature thermistor exceeds
discharge tempera- 111°C, compressor frequency lowers.
ture protection
Low discharge tem- Temperature of discharge temperature thermistor has been
perature protection 50°C or less for 20 minutes.
MUZ-GE25/33/35/42/50 The overcurrent fl ows into IGBT (Insulated Gate Bipolar tran-
PAM protection PAM: sistor: TR821) or the bus-bar voltage reaches 320 V or more,
Pulse Amplitude Modu- PAM stops and restarts.
lation
MUZ-GE60/71/80 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
Inverter P.C. board
0.5-second ON
70
Remedy
The unit is normal, but check the
following.
• Check if the indoor fi lters are
clogged.
• Check if the refrigerant is short.
• Check if the indoor/outdoor unit air
circulation is short cycled.
• Check the refrigerant circuit and
the refrigerant amount.
• Refer to 11-5. "Check of LEV".
• Refer to 11-5. "Check of outdoor
thermistors".
• Refer to 11-5. "Check of LEV".
• Check the refrigerant circuit and
the refrigerant 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.
• Check if the connector of the com-
pressor is correctly connected.
Refer to 11-5. "How to check
inverter/compressor".
MUZ-GE
Flashing →
25/33/35/
LED
42/50
MUZ-GE
60/71/80
Flashing
→
LED