Friedrich SM18N30*, SS14N10*, SS12N10*, SS15N30* Normal Function of Valve, Malfunction of Valve

TROUBLESHOOTING TOUCH TEST CHART: TO SERVICE REVERSING VALVES

NORMAL FUNCTION OF VALVE

VALVE	DISCHARGE TUBE from Compressor	SUCTION TUBE to Compressor	Tube to INSIDE COIL	Tube to OUTSIDE COIL	LEFT Pilot Capillary Tube	RIGHT Pilot Capillary Tube	NOTES:
OPERATING							* TEMPERATURE OF VALVE BODY
CONDITION
							** WARMER THAN VALVE BODY
	1	2	3	4	5	6	POSSIBLE CAUSES	CORRECTIONS
Normal Cooling	Hot	Cool	Cool	Hot	*TVB	TVB
			as (2)	as (1)
Normal Heating	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.
Valve will not								Deenergize solenoid, raise head pressure,
shift from cool								reenergize solenoid to break dirt loose.
	Hot	Cool	Cool,	Hot,	*TVB	Hot	Pilot valve okay. Dirt in one bleeder hole.	If unsuccessful, remove valve, wash
to heat.			as (2)	as (1)				out. Check on air before installing. If no
								movement, replace valve, add strainer to
								discharge tube, mount valve horizontally.
								Stop unit. After pressures equalize, restart
							Piston cup leak	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
			as (2)	as (1)				free. If still no shift, replace valve.
Valve will not								Raise head pressure, operate solenoid
			Cool,	Hot,			Both ports of pilot open. (Back seat port	to free
shift from cool	Hot	Cool			Hot	Hot		partially clogged port. If still no shift,
			as (2)	as (1)			did not close).
to heat.								replace
								valve.
	Warm	Cool	Cool,	Hot,	*TVB	Warm	Defective Compressor.	Replace compressor
			as (2)	as (1)
							Not enough pressure differential at start	Check unit for correct operating pressures
	Hot	Warm	Warm	Hot	*TVB	Hot	of stroke or not enough fl ow to maintain	and charge. Raise head pressure. If no
							pressure differential.	shift, use valve with smaller port.
							Body damage.	Replace valve
Starts to shift
	Hot	Warm	Warm	Hot	Hot	Hot	Both ports of pilot open.	Raise head pressure, operate solenoid. If
but does not								no shift, use valve with smaller ports.
complete	Hot	Hot	Hot	Hot	*TVB	Hot	Body damage.	Replace valve
reversal.							Valve hung up at mid-stroke. Pumping	Raise head pressure, operate solenoid. If
							volume of compressor not suffi cient to	no shift, use valve with smaller ports.
							maintain reversal.
								Raise head pressure, operate solenoid.
	Hot	Hot	Hot	Hot	Hot	Hot	Both ports of pilot open.	If no
								shift, replace valve.
Apparent	Hot	Cool	Hot,	Cool,	*TVB	*TVB	Piston needle on end of slide leaking.	Operate valve several times, then recheck.
			as (1)	as (2)				If excessive leak, replace valve.
leap in heat-
			Hot,	Cool,				Operate valve several times, then recheck.
ing.	Hot	Cool			**WVB	**WVB	Pilot needle and piston needle leaking.
			as (1)	as (2)				If 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.
								Raise head pressure, operate solenoid.
			Hot,	Cool,				Remove valve and wash out. Check on air
	Hot	Cool			Hot	*TVB	Dirt in bleeder hole.	before reinstalling, if no movement, replace
			as (1)	as (2)
Will not shift								valve. Add strainer to discharge tube.
								Mount valve horizontally.
from heat to
								Stop unit. After pressures equalize, restart
cool.
			Hot,	Cool,				with solenoid deenergized. If valve shifts,
	Hot	Cool			Hot	*TVB	Piston cup leak.	reattempt with compressor running. If it
			as (1)	as (2)
								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)

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