Mitsubishi Electronics SKM28ZD-S, SKM35ZD-S, SKM50ZD-S, SKM22ZD-S, SKM25ZD-S user manual

TIMER lamp ON

RUN lamp keeps flashing

RUN lamp ON

RUN lamp 2 time flash

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We are constantly trying to do better service to our customers by installing such judges that show abnormality of each function as follows:

Defrosting

If the outside temperature becomes low and humidity is high, the heat exchanger in the outdoor unit may frost over, which prevents efficient heating.

If this happens, the automatic defroster is activated and during defrosting the heating operation stops for 5 to 10 minutes.

• Both indoor and outdoor fans stop and the RUN light (green) blinks slowly (1.5 sec. ON, 0.5 sec. OFF) during defrosting.

• The outdoor unit may give off some steam during defrosting. This is to help the defrosting process and is not a defect.

• The HEAT operation resumes as soon as defrosting has been completed.

Self diagnosis function

If the outside temperature becomes extremely low, it would be better to use an additional source of heating.

If heating operation is performed when the outside temperature is high, room temperature may become higher than the set temperature.

The hot air circulation system takes a while before warming up the room temperature.

Characteristics of HEAT mode operation

Mechanism and capacity of HEAT mode operation

■ Mechanism

• The unit draws in heat from the cold outside air, transfers it indoors and heats the room. The heating capacity of the heat pump mechanism decreases when the outside air temperature gets colder.

RUN lamp

1 time flash

2 time flash

5 time flash

6 time flash

7 time flash

TIMER lamp

1 time flash

2 time flash

4 time flash

5 time flash

6 time flash

1 time flash

2 time flash

3 time flash

4 time flash

5 time flash

6 time flash

2 time flash

Description of trouble		Cause
	•	Broken heat exchanger sensor (1) wire, poorconnector
Heat exchanger sensor (1) error	•	connection
		Disconnected sensor
Room temperature sensor error	•	Broken room temperature sensor wire, poor connector connection
	• Broken heat exchanger sensor (2) wire, poor connector
Heat exchanger sensor (2) error	•	connection
		Disconnected sensor
Indoor fan motor error	•	Defective fan motor, poor connector connection
Closed service valve	•	Closed service valve
Heat exchanger sensor (1) error	•	Disconnected sensor
Outdoor temperature sensor error	•	Broken outdoor sensor wire, poor connector connection
Outdoor heat exchanger fluid pipe	•	Broken heat exchanger fluid pipe sensor wire, poor connector
sensor error		connection
Discharge pipe sensor error	•	Broken discharge pipe sensor wire, poor connector connection
Suction pipe sensor error	•	Broken suction pipe sensor wire, poor connector connection
Power transistor sensor error	•	Broken power transistor sensor wire, poor connector connection
Current cut	•	Compressor locking, open phase on compressor output,
		shortcircuit on power transformer, closed control valve
	• Broken power transformer, broken compressor wire
Trouble of outdoor unit	•	Broken discharge pipe sensor wire, poor connector connection
	•	Compressor blockage
Over current	•	Overload operation, overcharge
Over heat of power transistor	•	Cooling problem
Over heat of compressor	•	Gas shortage, defective discharge pipe sensor, closed control
		valve
Error of signal transmission	• Defective power supply, Broken signal wire, defective in/outdoor
		unit boards
	•	Defective compressor
Rotor lock	•	Open phase on compressor
	• Defective outdoor unit boards

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