Bryant R-22 service manual Check-Flo-RaterComponents, Vi. Reversing Valve

				PISTON BODY
	PISTON	FEEDER
		TUBES
(ORIENT AS SHOWN)
BRASS	STRAINER			PISTON
HEX NUT
				PISTON RETAINER
PISTON		TEFLON	BRASS	FLARE ADAPTER
		SEAL
RETAINER			HEX
			BODY	INTERNAL STRAINER

A91138

PRODUCTION EXCEPT 1992

Fig. 45—Check-Flo-Rater™ Components

A94004

If the service valve is to be replaced, a metal barrier must be inserted between the valve and the unit to prevent damaging the unit exterior from the heat of the brazing operations.

CAUTION: Wear safety glasses and gloves when han- dling refrigerants.

Pumpdown Procedure

Service valves provide a convenient shutoff valve useful for certain refrigeration-system repairs. System may be pumped down to make repairs on low side without losing complete refrigerant charge.

1.Attach pressure gage to suction service-valve gage port.

2.Front seat liquid-line valve.

3.Start unit in cooling mode. Run until suction pressure reaches 5 psig (35kPa). Do not allow compressor to pump to a vacuum.

4.Shut unit off. Front seat suction valve.

NOTE: All outdoor unit coils will hold only factory-supplied amount of refrigerant. Excess refrigerant, such as in long-line applications, may cause unit to relieve pressure through internal pressure-relief valve (indicated by sudden rise of suction pressure) before suction pressure reaches 5 psig (35kPa). If this occurs, shut off unit immediately, front seat suction valve, and recover remain- ing pressure.

V. CHECK-FLO-RATER™ (BYPASS-TYPE) HEAT PUMPS ONLY REFRIGERANT-METERING HOLE THROUGH IT. THE RETAINER FORMS A STOP FOR PISTON IN REFRIGERANT-BYPASS MODE AND A SEAL- ING SURFACE FOR LIQUID-LINE FLARE CONNECTION. (SEE FIG. 45.) TO CHECK, CLEAN, OR REPLACE PIS- TON:

RELIANT PRODUCTS EXCEPT 1992 PRODUCTION

1.Shut off power to unit.

2.Pump unit down using pumpdown procedure described in this service manual.

3.Loosen nut and remove liquid-line flare connection from Check-Flo-Rater™ .

4.Pull retainer out of body, being careful not to scratch flare-sealing surface. If retainer does not pull out easily, carefully use locking pliers to remove it.

—39—

5.Slide piston out by inserting a small, soft wire with small kinks through metering hole. Do not damage metering hole, sealing surface around piston cones, or fluted portion of piston.

6.Clean piston refrigerant-metering hole.

7.Install a new retainer O-ring or retainer assembly before reassembling bypass-type Check-Flo-Rater™ .

RELIANT AND CUBE PRODUCTS PRODUCED IN 1992

1.Shut off power to unit.

2.Reclaim outdoor-unit refrigerant.

3.Loosen brass hex nut and remove line from brass hex body.

4.Slide piston out by inserting a small, soft wire with small kinks through metering hole. Do not damage metering hole, sealing surface around piston cones, or fluted portion of piston.

5.Clean piston refrigerant-metering hole.

6.Always replace Teflon seal with new seal. Never try to reuse old seals.

7.Reassemble brass nut and brass hex body. Be sure orienta- tion is as shown in Fig. 45.

VI. REVERSING VALVE

In heat pumps, changeover between heating and cooling modes is accomplished with a valve that reverses flow of refrigerant in system. (See Fig. 46.) This reversing-valve device is easy to troubleshoot and replace. The reversing-valve solenoid can be checked with power off with an ohmmeter. Check for continuity and shorting to ground. With control-circuit (24v) power on, check for correct voltage at solenoid coil. Check for overheated solenoid. With unit operating, other items can be checked, such as frost or condensate water on refrigerant lines.

The sound made by a reversing valve as it begins or ends defrost is a ″ whooshing″ sound, as the valve reverses and pressures in system equalize. An experienced service technician detects this sound and uses it as a valuable troubleshooting tool.

Using a remote measuring device, check inlet and outlet line temperatures. DO NOT touch lines. If reversing valve is operating normally, inlet and outlet temperatures on appropriate lines should be close. Any difference would be due to heat loss or gain across valve body. Temperatures are best checked with a remote-reading, electronic-type thermometer with multiple probes. Route thermo- couple leads to inside of coil area through service-valve mounting- plate area underneath coil. Fig. 47 and 48 show test points (TP) on reversing valve for recording temperatures. Insulate points for more accurate reading.