Mitsubishi Electronics MUY-GE09NA, MUY-GE12NA, MUY-GE15NA, MUY-GE18NA Troubleshooting Check Table

10-3. TROUBLESHOOTING CHECK TABLE

No.	Symptom	LED indication	Abnormal point/	Condition		Remedy
			Condition
	Outdoor	1-time flash every	Outdoor power sys-	Overcurrent protection stop is continuously performed 3 times	•Reconnect connector of compressor.
1	unit does	2.5 seconds	tem	within 1 minute after the compressor gets started, or failure of re-	•Refer to 10-5. "How to check inverter/
	not oper-			start of compressor has repeated 24 times.	compressor".
	ate.				•Check stop valve.
			Outdoor thermistors	Discharge temperature thermistor, fin temperature thermistor, de-	•Refer to 10-5. "Check of outdoor
2				frost thermistor, outdoor heat exchanger temperature thermistor,	thermistors".
				P.C. board temperature thermistor or ambient temperature therm-
				istor 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 times.)
4		6-time flash	Serial signal	The communication fails between the indoor and outdoor unit for	•Refer to 10-5.	"How to check miswir-
		2.5 seconds OFF		3 minutes.	ing 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
6		14-time flash	Outdoor unit	Outdoor unit is defective.	•Refer to 10-2.2. "Flow chart of the de-
		2.5 seconds OFF	(Other abnormality)		tailed outdoor unit failure mode recall
					function".
	'Outdoor	2-time flash	Overcurrent protec-	Large current flows into intelligent power module.	•Reconnect connector of compressor.
7	unit stops	2.5 seconds OFF	tion	When overcurrent protection occurs within 10 seconds after	•Refer to 10-5. "How to check inverter/
	and re-			compressor starts, compressor restarts after 15 seconds.	compressor".
	starts 3				•Check stop valve.
	minutes
		3-time flash	Discharge tempera-	Temperature of discharge temperature thermistor exceeds 241°F	•Check refrigerant circuit and refrigerant
	later' is
8		2.5 seconds OFF	ture overheat protec-	(116°C), compressor stops. Compressor can restart if discharge	amount.
	repeated.					"Check of LEV".
			tion	temperature thermistor reads 212°F (100°C) or less 3 minutes	•Refer to 10-5.
				later.
		4-time flash	Fin temperature /P.C.	Temperature of fin temperature thermistor on the heat sink ex-	•Check around outdoor unit.
9		2.5 seconds OFF	board temperature	ceeds 167 ~ 176°F (75 ~ 80°C) or temperature of P.C. board tem-	•Check outdoor unit air passage.
			thermistor overheat	perature thermistor on the inverter P.C. board exceeds 158 ~ 167	•Refer to 10-5. "Check of outdoor fan
			protection	°F (70 ~ 75°C).	motor".
10		5-time flash	High pressure pro-	Temperature of indoor coil thermistor exceeds 158°F (70°C) in	•Check refrigerant circuit and refrigerant
		2.5 seconds OFF	tection	HEAT mode. Temperature of outdoor heat exchanger temperature	amount.
			(MUZ)	thermistor exceeds 158°F (70°C) in COOL mode.	•Check stop valve.
11		8-time flash	Compressor syn-	The waveform of compressor current is distorted.	•Reconnect connector of compressor.
		2.5 seconds OFF	chronous abnormal-		•Refer to 10-5. "How to check inverter/
			ity		compressor".
		10-time flash	Outdoor fan motor	Outdoor fan has stopped 3 times in a row within 30 seconds after	•Refer to 10-5. "Check of outdoor fan
12		2.5 seconds OFF		outdoor fan start-up.	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 normally.	•Refer to 10-5.	"How to check inverter/
		2.5 seconds OFF	of compressor		compressor".
14		13-time flash	DC voltage	DC voltage of inverter cannot be detected normally.	•Refer to 10-5.	"How to check inverter/
		2.5 seconds OFF			compressor".
15	Outdoor	1-time flash	Frequency drop by	Current from power outlet is nearing Max. fuse size.	The unit is normal, but check the follow-
	unit oper-	2.5 seconds OFF	current protection		ing.
	ates.				•Check if indoor filters are clogged.
		3-time flash	Frequency drop by	Temperature of indoor coil thermistor exceeds 131°F (55°C) in
					•Check if refrigerant is short.
		2.5 seconds OFF	high pressure protec-	HEAT mode, compressor frequency lowers.
					•Check if indoor/outdoor unit air circula-
			tion
16					tion is short cycled.
			Frequency drop by	Indoor coil thermistor reads 46°F (8°C) or less in COOL mode,
			defrosting in COOL	compressor frequency lowers.
			mode
		4-time flash	Frequency drop by	Temperature of discharge temperature thermistor exceeds 232°F	•Check refrigerant circuit and refrigerant
17		2.5 seconds OFF	discharge tempera-	(111°C), compressor frequency lowers.	amount.	"Check of LEV".
			ture protection		•Refer to 10-5.
					•Refer to 10-5. "Check of outdoor
					thermistors".
18	Outdoor	7-time flash	Low discharge tem-	Temperature of discharge temperature thermistor has been 122°F	•Refer to 10-5.	"Check of LEV".
	unit oper-	2.5 seconds OFF	perature protection	(50°C) or less for 20 minutes.	•Check refrigerant circuit and refrigerant
	ates.				amount.
		8-time flash	PAM protection PAM:	The overcurrent flows into IGBT (Insulated Gate Bipolar transis-	This is not malfunction. PAM protection
19		2.5 seconds OFF	Pulse Amplitude	tor: TR821) or the bus-bar voltage reaches 320 V or more, PAM	will be activated in the following cases:
			Modulation	stops and restarts.	1 Instantaneous power voltage drop
					(Short time power failure)
					2 When the power supply voltage is high.
		9-time flash	Inverter check mode	The connector of compressor is disconnected, inverter check	•Check if the connector of the compres-
20		2.5 seconds OFF		mode starts.	sor is correctly connected. Refer to
					10-5. "How to check inverter/compres-
					sor".

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”.

ON

OFF

2.5-second OFF

0.5-second ON

2.5-second OFF

0.5-second ON

Inverter P.C. board (Parts side)

LED

Flashing →

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