Sanyo THX2452, UHX2452, UHX0752, UHX1252 F04, F05, F22 Alarm Alarm code, Outdoor unit control PCB

Trouble Diagnosis

3. W-2WAY ECO-i Alarm Codes

F04, F05, F22 Alarm

Alarm code	F04, F05, F22
Alarm meaning	Compressor 1 discharge temperature sensor (DISCH1) trouble, compressor 2 discharge
	temperature sensor (DISCH2) trouble, Compressor 3 discharge temperature sensor (DISCH3) trouble.
Alarm conditions	(1) Discharge temp. of 212°F (100°C) or higher was detected 20 minutes or more after that
	compressor stopped operating.
	(2) Discharge temp. of 176°F (80°C) or higher was detected after all compressors had been
	stopped for 60 minutes or longer.
	(3) A/D step is 10 steps or less (short circuit).
Probable cause	(1) Sensor malfunction
	• Sensor element malfunction
	• Sensor wiring is partially disconnected, resulting in increased electrical resistance.
	This alarm does not occur when the wiring is cut or when the connector is not connected to
	the outdoor unit control PCB.
	(2) Crossed wiring or installation error
	• The discharge temperature sensor of that compressor is connected to the discharge tube
	of the other compressor.
	• The connector for the discharge temperature sensor of the problem compressor is
	connected to the outdoor unit PCB connector for the other compressor.
	(3) Outdoor unit PCB failure
	(4) The check valve on the discharge tube for that compressor is wet.
	(5) An air short blockage in the area around the outdoor unit has increased the outdoor unit
	ambient temperature, reducing the cooling effects after the compressor stops.
	(6) There is a cause that results in P03, P17, or P18 alarm.
Check	(1) Sensor malfunction and outdoor unit PCB failure
	Trouble: • Constantly indicates a high temperature.
		• When monitoring software or other means are used for monitoring, the discharge
		temperature at times fluctuates suddenly and wildly.
		• In some cases, the precise temperature may not be known, even when monitoring
		software is used.
	Check:	• Wiggle the sensor and check whether the trouble continues.
		• Check whether the connector is partially disconnected from the PCB.
		An F04 alarm will not result if the connector is completely disconnected (circuit is
		open).
		• If the cause is still uncertain, check the following to determine whether a sensor or
		PCB failure has occurred.
		Step 1: Connect the other compressor discharge sensor, or a discharge sensor where
		the F04 alarm has not occurred, to the connector for this compressor on the
		PCB. Measure the temperature at the same point (a location where
		temperature fluctuations are small), and check whether there is a temperature
		difference.	→ A PCB or sensor failure is possible.
		Difference
		No difference → PCB and sensor are normal.
		Step 2: If an abnormality was found at Step 1, connect the problem compressor
		sensor to the other compressor connector on the PCB, or to the PCB
		connector of a device where the F04 alarm has not occurred. Measure the
		temperature at the same point (a location where temperature fluctuations are
		small), and check whether there is a temperature difference.
		Difference	→ Sensor failure.
		No difference → PCB failure.
		It is convenient at this time to have a discharge temperature sensor on hand.
	(2) Crossed wiring or installation error
	Trouble: Although the other compressor is operating and this compressor is stopped, the
		discharge temperature of the other compressor does not increase and the discharge
		temperature of this compressor rises.
		* The discharge temperature remains high immediately after the compressor stops. Wait
		for some time after the compressor stops and observe.
	Check:	Check for crossed wiring and installation errors.
			Continued

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