Sanyo XH3642 / CH3642, XH4242 / CH4242 Service procedures Checking procedure for each PC Board

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4. Service procedures

(12) Checking procedure for each PC Board

The indoor and outdoor PCBs have functions to check the signal transmission and reception of the serial circuit and to check the microcomputer operation. (Self-diagnosis function)

●Precautions required when checking

1.After turning off the power to the indoor (outdoor) unit, remove the inter-unit control wiring (U1-U2) and create a short-circuit between U1 and U2.

2.Short the CHECK PIN on the PC board of the indoor (outdoor) unit and turn on the power.

3.When checking the Outdoor controller, remove the compressor wiring from the compressor electromagnetic contactor.

4-1. Checking the serial circuit

Indoor controller: A lighted LED indicates normal. A blinking LED indicates abnormal.

Outdoor controller: Blinking LEDs (D11 and D22) indicate normal. If one of the LEDs (D11 and D22) goes off, it indicates abnormal.

4-2. Checking microcomputer operation

When the microcomputer works normally, the relays are switched in sequence as below.

Indoor controller

			Output		ON time
		Indoor fan	Very high fan speed (HH)		0.5 seconds
		Indoor fan	High fan speed (H)		0.5 seconds
		Indoor fan	Low fan speed (L)		0.5 seconds
		Indoor fan	Very low fan speed (LL)		0.5 seconds
		Flap motor			0.5 seconds
		Drain pump			0.5 seconds
Operation order	Electric heater				0.5 seconds
		Operation signal			0.5 seconds
		In a lump			0.5 seconds
		Electronic control valve A			0.5 seconds
		Electronic control valve B			0.5 seconds
		Electronic control valve.A			0.5 seconds
		Electronic control valve		B	0.5 seconds
		Outdoor controller
			Output		ON time
		Outdoor fan	High fan speed (H)		0.5 seconds
Operation order		Outdoor fan	Low fan speed (L)		0.5 seconds
	4-way valve			0.5 seconds
		Compressor			0.5 seconds

SM830082

IV - 44