Friedrich 2003 service manual Troubleshooting Touch Test Chart To Service Reversing Valves

Troubleshooting Touch Test Chart: To Service Reversing Valves

VALVE

OPERATING CONDITION

Normal

Cooling

Normal Heating

Valve will not shift from cool to heat.

Valve will

not shift

from cool to

heat.

Starts to shift but does not complete reversal.

Apparent

leap in

heating.

Will not shift from heat to cool.

						NORMAL FUNCTION OF VALVE
TUBE	from		INSIDEtoTube COIL	OUTSIDEtoTube COIL	PilotLEFT CapillaryTube	PilotRIGHT CapillaryTube	NOTES:
	Compressor	TUBE
DISCHARGE		Compressor
		SUCTIONto					* TEMPERATURE OF VALVE BODY
							** WARMER THAN VALVE BODY

1	2	3	4	5	6	POSSIBLE CAUSES	CORRECTIONS
Hot	Cool	Cool	Hot	*TVB	TVB
		as (2)	as (1)
Hot	Cool	Hot	Cool	*TVB	TVB
		as (1)	as (2)
				MALFUNCTION OF VALVE
	Check Electrical circuit and coil					No voltage to coil.	Repair electrical circuit.
						Defective coil.	Replace coil.
	Check refrigeration charge					Low charge.	Repair leak, recharge system.
						Pressure differential too high.	Recheck system.
Hot	Cool	Cool,	Hot,	*TVB	Hot	Pilot valve okay. Dirt in one	Deenergize solenoid, raise head pressure,
		as (2)	as (1)			bleeder hole.	reenergize solenoid to break dirt loose. If
							unsuccessful, remove valve, wash out. Check
							on air before installing. If no movement, replace
							valve, add strainer to discharge tube, mount
							valve horizontally.
						Piston cup leak	Stop unit. After pressures equalize, restart with
							solenoid energized. If valve shifts, reattempt
							with compressor running. If still no shift, replace
							valve.
Hot	Cool	Cool,	Hot,	*TVB	*TVB	Clogged pilot tubes.	Raise head pressure, operate solenoid to free.
		as (2)	as (1)				If still no shift, replace valve.
Hot	Cool	Cool,	Hot,	Hot	Hot	Both ports of pilot open. (Back seat	Raise head pressure, operate solenoid to free
		as (2)	as (1)			port did not close).	partially clogged port. If still no shift, replace
		Cool,	Warm,				valve.
Warm	Cool			*TVB	Warm	Defective Compressor.	Replace compressor
		as (2)	as (1)
Hot	Warm	Warm	Hot	*TVB	Hot	Not enough pressure differential at	Check unit for correct operating pressures and
						start of stroke or not enough flow to	charge. Raise head pressure. If no shift, use
						maintain pressure differential.	valve with smaller port.
		Warm	Hot			Body damage.	Replace valve
Hot	Warm			Hot	Hot	Both ports of pilot open.	Raise head pressure, operate solenoid. If no
Hot	Hot	Hot	Hot				shift, replace valve.
				*TVB	Hot	Body damage.	Replace valve
						Valve hung up at mid-stroke. Pumping	Raise head pressure, operate solenoid. If no
						volume of compressor not sufficient to	shift, use valve with smaller ports.
		Hot,	Hot			maintain reversal.
Hot	Hot			Hot	Hot	Both ports of pilot open.	Raise head pressure, operate solenoid. If no
Hot	Cool	Hot,	Cool,				shift, replace valve.
				*TVB	*TVB	Piston needle on end of slide leaking.	Operate valve several times, then recheck. If
		as (1)	as (2)				excessive leak, replace valve.
Hot	Cool	Hot,	Cool,	**	**	Pilot needle and piston needle leaking.	Operate valve several times, then recheck. If
		as (1)	as (2)	WVB	WVB		excessive leak, replace valve.
Hot	Cool	Hot,	Cool,	*TVB	*TVB	Pressure differential too high.	Stop unit. Will reverse during equalization
		as (1)	as (2)				period. Recheck system
						Clogged pilot tube.	Raise head pressure, operate solenoid to free
							dirt. If still no shift, replace valve.
Hot	Cool	Hot,	Cool,	Hot	*TVB	Dirt in bleeder hole.	Raise head pressure, operate solenoid.
		as (1)	as (2)				Remove valve and wash out. Check on air
							before reinstalling, if no movement, replace
							valve. Add strainer to discharge tube. Mount
							valve horizontally.
Hot	Cool	Hot,	Cool,	Hot	*TVB	Piston cup leak.	Stop unit. After pressures equalize, restart with
		as (1)	as (2)				solenoid deenergized. If valve shifts, reattempt
							with compressor running. If it still will not reverse
							while running, replace the valve.
Hot	Cool	Hot,	Cool,	Hot	Hot	Defective pilot.	Replace valve.
		as (1)	as (2)
Warm	Cool	Warm,	Cool,	Warm	*TVB	Defective compressor.	Replace compressor
		as (1)	as (2)

35