Sanyo CH0971, CH1271 service manual Basic Functions of the Service Valves, Pump Down

■Basic Functions of the Service Valves

The basic functions of the service valves are given in Table 8 below.

Table 8

Action	Narrow Tube Service	Wide Tube Service
	Valve (2-Way)	Valve (3-Way)
	CLOSED	O-ring	Valve cap
			Stem

Shipping

Fully OPEN

Operating and test running

the air conditioner

	Fully OPEN
Measuring pressure		*
and gas charging
	CLOSED
Air purging with		*	* The service port on the wide tube ser-
			vice valve uses a Schrader core valve
a vacuum pump			to access the refrigerant system.
			Therefore, be sure to use a hose con-
			nector which has a push-pin inside.
			(Fig. 60a)
			Service valve
CAUTION		Hose with push-pin
		Close
When opening or clos-			PUSH
ing the service valve
	Open
stem, use the accessory		Hex	NOTE
hex wrench. Be sure to		wrench
			External diameter of service port
fully seat the wrench		Fig. 60b
before turning the valve.			R410A: 5/16"

Fig. 60a

■Pump Down

Pump down means collecting all refrigerant gas in the system back into the outdoor unit without losing any of the gas. Pump down is used when the unit is to be moved or before servicing the refrigerant circuit.

Pump Down Procedure

Be sure to carry out pump down with the unit in cooling mode.

(1)Connect the Lo side charging hose of the manifold valve to the service port on the wide tube service valve.

(2)Using a hex wrench, turn the narrow tube service valve clockwise all the way to close the service valve. (Be sure to confirm that the wide tube service valve is fully open.)

(3)Press the operation button and start cooling oper- ation.

(4)When the low pressure gauge reading falls to 14.2 to 7.1 psi (1 to 0.5 kg/cm2), fully close the wide tube valve stem. Then quickly stop the unit.

(5)Disconnect all gauges and hoses, and replace the valve caps as they were before.

22