Mitsubishi Electronics MUZ-D36NA, MUY-D36NA, U1, MUZ-D30NA Troubleshooting Check Table, LED1 LED2

10-3. TROUBLESHOOTING CHECK TABLE

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

No.	Symptom	Indication		Abnormal point / Condition	Condition		Correspondence
		LED1	LED2
		(Red)	(Yellow)
					IPM protection stop or lock protection stop is continuously	• Check the connection of the compressor connect-
						ing wire.
					performed three times within 1 minute after the compressor		"How to check inverter/compres-
1		Lightning	Twice	Outdoor power system		• Refer to 10-5.
					gets started, or converter protection stop or bus-bar voltage
						sor".
					protection stop is continuously performed 3 times within 3
						• Refer to 10-5.	"Check of compressor start failure".
					minutes after start-up.
						• 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".
				istor	tion, or an open circuit is detected in the thermistor after 10
					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-
					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.
					A short circuit is detected in the thermistor during operation,
	unit does			Outdoor heat exchanger
					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".
				temperature thermistor	(in cooling) and 10 minutes (in heating (MUZ)) of compressor
	ate.
					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
					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.
					twice.
8		Lightning	11 times	Communication error between	The communication protection stop between boards is con-	• Check the connecting wire between outdoor elec-
				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-
						tronic control P.C. board, noise filter P.C. board and
					continuously performed 10 times.
						power board.
				IPM protection	Overcurrent is detected after 30 minutes of compressor start-	• Reconnect compressor connector.
					up.	• Refer to 10-5.	"How to check inverter/compres-
10		Twice	Goes out			sor".
				Lock protection	Overcurrent is detected within 30 minutes of compressor	• Refer to 10-5.	"Check of compressor start failure".
					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		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
						• 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.
	unit stops				°C) during cooling or indoor gas pipe temperature exceeds	• Check of stop valve.
					158 °F (70 °C) during heating (MUZ).
	and restarts
14	3 minutes	8 times	Goes out	Converter protection	A failure is detected in the operation of the converter during	• 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.
				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".
					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-
					control P.C. board and power board for more than 10 sec-
				boards protection		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-
				protection	operating.	tronic control P.C. board, noise filter P.C. board and
						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

ON

OFF

2.5-second OFF

Lighting

0.5-second ON 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”.

25