Mitsubishi Electronics MUZ-FD09NA service manual Troubleshooting Check Table

10-3. TROUBLESHOOTING CHECK TABLE

No.	Symptom	LED indication	Abnormal point/	Condition	Correspondence
			Condition
	Outdoor unit	1-time flash every	Outdoor power sys-	Overcurrent protection stop is continuously performed 3 times	•Reconnect connector of compres-
1	does not oper-	2.5 seconds	tem	within 1 minute after the compressor gets started, or failure of	sor.
	ate.			restart of compressor has repeated 24 times.	•Refer to 10-5. "How to check in-
					verter/ compressor".
					•Check stop valve.
			Outdoor thermistors	Discharge temperature thermistor, fin temperature thermistor,	•Refer to 10-5. "Check of outdoor
2				defrost thermistor, P.C. board temperature thermistor or ambi-	thermistors".
				ent temperature thermistor shorts or opens during compressor
				running.
3			Outdoor control sys-	Nonvolatile memory data cannot be read properly.	•Replace inverter P.C. board.
			tem	(POWER lamp of the indoor unit lights up or flashes 7-time.)
4		6-time flash	Serial signal	The communication fails between the indoor and outdoor unit	•Refer to 10-5.	"How to check
		2.5 seconds OFF		for 3 minutes.	miswiring and serial signal error.
5		11-time flash	Stop valve/	Closed valve is detected by compressor current.	•Check stop valve.
		2.5 seconds OFF	Closed valve
		14-time flash	Outdoor unit	Outdoor unit is defective.	•Refer to 10-2.2. "Flow chart of the
6		2.5 seconds OFF	(Other abnormality)		detailed outdoor unit failure mode
					recall function".
	'Outdoor unit	2-time flash	Overcurrent protec-	Large current flows into intelligent power module.	•Reconnect connector of compres-
7	stops and	2.5 seconds OFF	tion	When overcurrent protection occurs within 10 seconds after	sor.
	restarts 3 min-			compressor starts, compressor restarts after 15 seconds.	•Refer to 10-5. "How to check in-
	utes later' is				verter/compressor".
	repeated.				•Check stop valve.
		3-time flash	Discharge tempera-	Temperature of discharge temperature thermistor exceeds 241	•Check refrigerant circuit and refrig-
8		2.5 seconds OFF	ture overheat protec-	°F (116 °C), compressor stops. Compressor can restart if dis-	erant amount.
			tion	charge temperature thermistor reads 212 °F (100 °C) or less 3	•Refer to 10-5.	"Check of LEV".
				minutes later.
		4-time flash	Fin temperature /P.C.	Temperature of fin temperature thermistor on the heat sink ex-	•Check around outdoor unit.
		2.5 seconds OFF	board temperature	ceeds 167 ~ 176 °F (75 ~ 80 °C) or temperature of P.C. board	•Check outdoor unit air passage.
9			thermistor overheat	temperature thermistor on the inverter P.C. board exceeds 158	•Refer to 10-5. "Check of outdoor
			protection	~ 167 °F (70 ~ 75 °C).	fan motor".
10		5-time flash	High pressure pro-	Indoor coil thermistor exceeds 158 °F (70 °C) in HEAT mode.	•Check refrigerant circuit and refrig-
		2.5 seconds OFF	tection	Defrost thermistor exceeds 158 °F (70 °C) in COOL mode.	erant amount.
					•Check stop valve.
		8-time flash	Compressor syn-	The waveform of compressor current is distorted.	•Reconnect connector of compres-
11		2.5 seconds OFF	chronous abnormal-		sor.
			ity		•Refer to 10-5. "How to check in-
					verter/compressor".
		10-time flash	Outdoor fan motor	Outdoor fan has stopped 3 times in a row within 30 seconds	•Refer to 10-5. "Check of outdoor
12		2.5 seconds OFF		after outdoor fan start-up.	fan motor.
					•Refer to 10-5. "Check of inverter
					P.C. board.
13		12-time flash	Each phase current	Each phase current of compressor cannot be detected nor-	•Refer to 10-5.	"How to check in-
		2.5 seconds OFF	of compressor	mally	verter/compressor".
14		13-time flash	DC voltage	DC voltage of inverter cannot be detected normally.	•Refer to 10-5.	"How to check in-
		2.5 seconds OFF			verter/compressor".
15	Outdoor unit	1-time flash	Frequency drop by	Current from power outlet reaches the protection current, and	The unit is normal, but check the
	operates.	2.5 seconds OFF	current protection	compressor frequency lowers.	following.
					•Check if indoor filters are clogged.
		3-time flash	Frequency drop by	Temperature of indoor coil thermistor exceeds 131 °F (55 °C)
					•Check if refrigerant is short.
		2.5 seconds OFF	high pressure pro-	in HEAT mode, compressor frequency lowers.
					•Check if indoor/outdoor unit air cir-
			tection
16					culation is short cycled.
			Frequency drop by	Indoor coil thermistor reads 46 °F (8 °C) or less in COOL
			defrosting in COOL	mode, compressor frequency lowers.
			mode
		4-time flash	Frequency drop by	Temperature of discharge temperature thermistor exceeds 232	•Check refrigerant circuit and refrig-
17		2.5 seconds OFF	discharge tempera-	°F (111 °C), compressor frequency lowers.	erant amount.	"Check of LEV".
			ture protection		•Refer to 10-5.
					•Refer to 10-5. "Check of outdoor
					thermistors".

NOTE: 1. The location of LED is illustrated at the right figure. Refer to 10-6.1. 2. LED is lighted during normal operation.

The flashing frequency shows the number of times the LED blinks after every 2.5-second OFF. Flashing (Example) When the flashing frequency is “2”.

Inverter P.C. board(Parts side)

LED

Flashing →

ON

OFF

2.5-second OFF

0.5-second ON 0.5-second ON

2.5-second OFF

20