Troubleshooting Check Table | Mitsubishi Electronics MUZ-D36NA, U1

10-3. TROUBLESHOOTING CHECK TABLE

MUZ-D30NA MUZ-D36NA MUY-D30NA MUY-D36NA

No.	Symptom	Indication		Abnormal point / Condition	Condition		Correspondence
No.	Symptom	LED1	LED2	Abnormal point / Condition	Condition		Correspondence
		(Red)	(Yellow)
					IPM protection stop or lock protection stop is continuously	• Check the connection of the compressor connect-
					IPM protection stop or lock protection stop is continuously	ing wire.
					performed three times within 1 minute after the compressor	ing wire.	"How to check inverter/compres-
1		Lightning	Twice	Outdoor power system	performed three times within 1 minute after the compressor	• Refer to 10-5.
					gets started, or converter protection stop or bus-bar voltage	• Refer to 10-5.
						sor".
					protection stop is continuously performed 3 times within 3	sor".
					protection stop is continuously performed 3 times within 3	• Refer to 10-5.	"Check of compressor start failure".
					minutes after start-up.	• Refer to 10-5.	"Check of compressor start failure".
					minutes after start-up.	• Check the stop valve.
						• Check the stop valve.
2		Lightning	3 times	Discharge temperature therm-	A short circuit is detected in the thermistor during opera-	• Refer to 10-5.	"Check of outdoor thermistor".
2		Lightning	3 times	istor	tion, or an open circuit is detected in the thermistor after 10	• Refer to 10-5.	"Check of outdoor thermistor".
				istor	minutes of compressor start-up.
					minutes of compressor start-up.
3		Lightning	4 times	Fin temperature thermistor	A short or open circuit is detected in the thermistor during	• Refer to 10-5.	"Check of outdoor thermistor".
				P.C. board temperature therm-
				P.C. board temperature therm-	operation.	• Replace the outdoor electronic control P.C. board.
				istor
				Ambient temperature thermis-	A short or open circuit is detected in the thermistor during
	Outdoor			tor	operation.
	Outdoor				A short circuit is detected in the thermistor during operation,
	unit does			Outdoor heat exchanger
	unit does				or an open circuit is detected in the thermistor after 5 minutes
4	not oper-	Lightning	5 times			• Refer to 10-5.	"Check of outdoor thermistor".
	not oper-			temperature thermistor	(in cooling) and 10 minutes (in heating (MUZ)) of compressor
	ate.			temperature thermistor
	ate.				start-up.
					start-up.
					A short circuit is detected in the thermistor during operation,
				Defrost thermistor (MUZ)	or an open circuit is detected in the thermistor after 5 minutes
					of compressor start-up.
5		Lightning	6 times	Serial signal	The communication fails between the indoor and outdoor unit	• Refer to 10-5.	"How to check miswiring and serial
5		Lightning	6 times	Serial signal	for 3 minutes.	signal error.
					for 3 minutes.	signal error.
6		Lightning	7 times	Nonvolatile memory data	The nonvolatile memory data cannot be read properly.	• Replace the outdoor electronic control P.C. board.
7		Lightning	8 times	Current sensor	Current sensor protection stop is continuously performed	• Replace the power board.
7		Lightning	8 times	Current sensor	twice.	• Replace the power board.
					twice.
8		Lightning	11 times	Communication error between	The communication protection stop between boards is con-	• Check the connecting wire between outdoor elec-
8		Lightning	11 times	P.C. boards	tinuously performed twice.	tronic control P.C. board and power board.
				P.C. boards	tinuously performed twice.	tronic control P.C. board and power board.
9		Lightning	12 times	Zero cross detecting circuit	The protection stop of the zero cross detecting circuit is	• Check the connecting wire among outdoor elec-
					The protection stop of the zero cross detecting circuit is	tronic control P.C. board, noise ﬁlter P.C. board and
					continuously performed 10 times.	tronic control P.C. board, noise ﬁlter P.C. board and
					continuously performed 10 times.	power board.
						power board.
				IPM protection	Overcurrent is detected after 30 minutes of compressor start-	• Reconnect compressor connector.
				IPM protection	up.	• Refer to 10-5.	"How to check inverter/compres-
					up.	• Refer to 10-5.	"How to check inverter/compres-
10		Twice	Goes out			sor".
10		Twice	Goes out	Lock protection	Overcurrent is detected within 30 minutes of compressor	• Refer to 10-5.	"Check of compressor start failure".
					Overcurrent is detected within 30 minutes of compressor	• Refer to 10-5.	"Check of compressor start failure".
					start-up	• Check the stop valve.
					start-up	• Check the stop valve.
						• Check the power module (PAM module).
				Discharge temperature protec-	Temperature of discharge temperature thermistor exceeds
11		3 times	Goes out	Discharge temperature protec-	241 °F (116 °C), compressor stops. Compressor can restart	• Check the amount of gas and refrigerant circuit.
				tion	if discharge temperature thermistor reads 212 °F (100 °C) or	• Refer to 10-5.	"Check of LEV".
					less 3 minutes later.
12		4 times	Goes out	Fin temperature protection	The ﬁn temperature exceeds 189 °F (87 °C) during operation.	• Check refrigerant circuit and refrigerant amount.
				P.C. board temperature pro-	The P.C. board temperature exceeds 158 °F (70 °C) during	• Check refrigerant circuit and refrigerant amount.
				P.C. board temperature pro-	The P.C. board temperature exceeds 158 °F (70 °C) during	• Refer to 10-5.	"Check of LEV".
				tection	operation.	• Refer to 10-5.	"Check of LEV".
				tection	operation.
13	'Outdoor	5 times	Goes out	High-pressure protection	The outdoor heat exchanger temperature exceeds 158 °F (70	• Check around of gas and the refrigerant circuit.
13	unit stops	5 times	Goes out	High-pressure protection	°C) during cooling or indoor gas pipe temperature exceeds	• Check of stop valve.
	unit stops				158 °F (70 °C) during heating (MUZ).	• Check of stop valve.
	and restarts				158 °F (70 °C) during heating (MUZ).
14	3 minutes	8 times	Goes out	Converter protection	A failure is detected in the operation of the converter during	• Replace the power board.
14	later' is	8 times	Goes out	Converter protection	operation.	• Replace the power board.
	later' is				operation.
	repeated.			Bus-bar voltage protection (1)	The bus-bar voltage exceeds 400 V or falls to 200 V or below
15		9 times	Goes out		during compressor operating.	• Replace the power board.
15		9 times	Goes out	Bus-bar voltage protection (2)	The bus-bar voltage exceeds 400 V or falls to 50 V or below	• Replace the power board.
				Bus-bar voltage protection (2)	The bus-bar voltage exceeds 400 V or falls to 50 V or below
					during compressor operating.
16		13 times	Goes out	Outdoor fan motor	Failure occurs continuously three times within 30 seconds	• Refer to 10-5.	"Check of outdoor fan motor".
16		13 times	Goes out	Outdoor fan motor	after the fan gets started.	• Refer to 10-5.	"Check of outdoor fan motor".
					after the fan gets started.
17		Lighting	8 times	Current sensor protection	A short or open circuit is detected in the current sensor during	• Replace the power board.
					compressor operating.
18		Lighting	11 times	Communication between P.C.	Communication error occurs between the outdoor electronic	• Check the connecting wire between outdoor elec-
				Communication between P.C.	control P.C. board and power board for more than 10 sec-	• Check the connecting wire between outdoor elec-
				boards protection	control P.C. board and power board for more than 10 sec-	tronic control P.C. board and power board.
				boards protection	onds.	tronic control P.C. board and power board.
					onds.
19		Lighting	12 times	Zero cross detecting circuit	Zero cross signal cannot be detected while the compressor is	• Check the connecting wire among outdoor elec-
19		Lighting	12 times	protection	operating.	tronic control P.C. board, noise ﬁlter P.C. board and
				protection	operating.	power board.
						power board.

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

Outdoor electronic control P.C. board(Parts side)

LED2 LED1

OFF

2.5-second OFF

Lighting

0.5-second ON

2.5-second OFF

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

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