Panasonic CU-4KS31NBU service manual Electric expansion valve

(6) Electric expansion valve

When replacing the electric expansion valve and coil, be sure to attach the connectors in the correct positions. Labels are applied to the valve body and coil, corresponding to the connector colors, to identify them.

Controller check

No voltage on circuit board Voltage varies

Use a multi-meter to measure the voltage (12 V).

When the power is turned ON, the needle will move in the following seguence in approximately 10 to 20 seconds for each point.

Model No.		Sequence
CU-3KS19NBU	MV0	MV1	MV2
CU-4KS24NBU	MV0	MV1	MV2	MV3
CU-4KS31NBU

Check the illumination of the red Power Lamp.

Replace the controller.

NOTE

Cool the main unit with a damp cloth or other means while welding. When applying vacuum, use the special service magnet and rotate at least 5 revolutions counterclockwise to fully open the electric expansion valve.

Check the coil resistance.		Check the resistance between the gray lead
		wire and the other wires.
		Resistance is OK if it is 46 + / – 4ohm at 68 °F
0 ohm	Approx. 46 +/– 4 ohm

			*1		Use the special service magnet and
Replace the coil.
		Open and close the
					rotate 5 revolutions clockwise to fully
		electric expansion valve			close the valve.
		by hand to check it.			Then start the unit and measure the
					temperature at the inlet and outlet
	No temperature change			Temperature changes	tubes of the electric expansion valve.
					If the temperature difference is large,
					the valve is closed.
					Then rotate 5 revolutions
	Replace the electric			This part is normal.	counterclockwise to open the valve.
	expansion valve.			Check elsewhere.	Operation is normal if the temperature
					difference between the 2 tubes drops.

*1 If you have manually checked the electric expansion valve, be sure to reapply the outdoor power after you have replaced the wiring. (The position of the elecric expansion valve will changed.)

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