Friedrich 2007 service manual Normal Function of Valve, Malfunction of Valve

TROUBLESHOOTING TOUCH TEST CHART: TO SERVICE REVERSING VALVES

NORMAL FUNCTION OF VALVE

VALVE	DISCHARGETUBE fromCompressor	SUCTIONTUBEto Compressor	Tube toINSIDE COIL	TubeOUTSIDEto COIL	LEFT Pilot CapillaryTube	RIGHT Pilot	CapillaryTube	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	Hot	Cool	Cool,	Hot,	*TVB	Hot		De-energize solenoid, raise head pres-
			as (2)	as (1)				sure, reenergize solenoid to break dirt
shift from cool							Pilot valve okay. Dirt in one bleeder hole.	loose. If unsuccessful, remove valve, wash
to heat.								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
			Cool,	Hot,			Both ports of pilot open. (Back seat port did	Raise head pressure, operate solenoid to
shift from cool	Hot	Cool			Hot	Hot		free partially clogged port. If still no shift,
			as (2)	as (1)			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 of	Check unit for correct operating pressures
	Hot	Warm	Warm	Hot	*TVB	Hot	stroke or not enough flow to maintain pres-	and charge. Raise head pressure. If no
							sure differential.	shift, use valve with smaller port.
Starts to shift							Body damage.	Replace valve
	Hot	Warm	Warm	Hot	Hot	Hot	Both ports of pilot open.	Raise head pressure, operate solenoid.
but does not								If 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 vol-	Raise head pressure, operate solenoid.
							ume of compressor not sufficient to maintain	If no shift, use valve with smaller ports.
							reversal.
	Hot	Hot	Hot	Hot	Hot	Hot	Both ports of pilot open.	Raise head pressure, operate solenoid.
								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 heating.	Hot	Cool	Hot,	Cool,	** WVB	** WVB	Pilot needle and piston needle leaking.	Operate valve several times, then recheck.
			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
	Hot	Cool			Hot	*TVB	Dirt in bleeder hole.	air before reinstalling, if no movement,
Will not shift			as (1)	as (2)
								replace valve. Add strainer to discharge
from heat to								tube. Mount valve horizontally.
								Stop unit. After pressures equalize, restart
cool.
			Hot,	Cool,				with solenoid de-energized. 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)

16