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DISCHARGE TUBE
SUCTION TUBE to
Tube to OUTSIDE
from Compressor
Tube to INSIDE
Capillary Tube
Capillary Tube
Compressor
RIGHT Pilot
LEFT Pilot
COIL
COIL
14
NORMAL FUNCTION OF VALVE
VALVE
OPERATING
DISCHARGE TUBE
from Compressor
SUCTION TUBE
to Compressor
Tube to INSIDE
COIL
Tube to OUTSIDE
COIL
LEFT Pilot
Capillary Tube
RIGHT Pilot
Capillary Tube
CONDITION
NOTES:
* TEMPERATURE OF VALVE BODY
** WARMER THAN VALVE BODY
1 2 3 4 5 6 POSSIBLE CAUSES CORRECTIONS
Normal Cooling
Hot Cool
Cool
as (2)
Hot
as (1)
*TVB TVB
Normal Heating
Hot Cool
Hot
as (1)
Cool
as (2)
*TVB TVB
MALFUNCTION OF VALVE
Valve will not
shift from cool
to heat.
Check Electrical circuit and coil
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Check refrigeration charge
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Pressure dif
ferential too high. Recheck system.
Hot Cool
Cool,
as (2)
Hot,
as (1)
*TVB Hot Pilot valve okay. Dirt in one bleeder hole.
Deenergize solenoid, raise head pressure,
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.
Valve will not
shift from cool
to heat.
Hot Cool
Cool,
as (2)
Hot,
as (1)
*TVB *TVB Clogged pilot tubes.
Raise head pressure, operate solenoid to
free. If still no shift, replace valve.
Hot Cool
Cool,
as (2)
Hot,
as (1)
Hot Hot
Both ports of pilot open. (Back seat port
did not close).
Raise head pressure, operate solenoid
to free
partially clogged port. If still no shift,
replace
valve.
Warm Cool
Cool,
as (2)
Hot,
as (1)
*TVB Warm Defective Compressor. Replace compressor
Starts to shift
but does not
complete
reversal.
Hot Warm Warm Hot *TVB Hot
Not enough pressure differential at start
of stroke or not enough f ow to maintain
pressure differential.
Check unit for correct operating pressures
and charge. Raise head pressure. If no
shift, use valve with smaller port.
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Hot Warm Warm Hot Hot Hot Both ports of pilot open.
Raise head pressure, operate solenoid. If
no shift, use valve with smaller ports.
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Valve hung up at mid-stroke. Pumping
volume of compressor not suff cient to
maintain reversal.
Raise head pressure, operate solenoid. If
no shift, use valve with smaller ports.
Hot Hot Hot Hot Hot Hot Both ports of pilot open.
Raise head pressure, operate solenoid.
If no
shift, replace valve.
Apparent
leap in heat-
ing.
Hot Cool
Hot,
as (1)
Cool,
as (2)
*TVB *TVB Piston needle on end of slide leaking.
Operate valve several times, then recheck.
If excessive leak, replace valve.
Hot Cool
Hot,
as (1)
Cool,
as (2)
**WVB **WVB Pilot needle and piston needle leaking.
Operate valve several times, then recheck.
If excessive leak, replace valve.
Will not shift
from heat to
cool.
Hot Cool
Hot,
as (1)
Cool,
as (2)
*TVB *TVB Pressure differential too high.
Stop unit. Will reverse during equalization
period. Recheck system
Clogged pilot tube.
Raise head pressure, operate solenoid to
free dirt. If still no shift, replace valve.
Hot Cool
Hot,
as (1)
Cool,
as (2)
Hot *TVB Dirt in bleeder hole.
Raise head pressure, operate solenoid.
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,
as (1)
Cool,
as (2)
Hot *TVB Piston cup leak.
Stop unit. After pressures equalize, restart
with solenoid deenergized. If valve shifts,
reattempt with compressor running. If it
still will not reverse while running, replace
the valve.
Hot Cool
Hot,
as (1)
Cool,
as (2)
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Warm Cool
Warm,
as (1)
Cool,
as (2)
Warm *TVB Defective compressor. Replace compressor
TROUBLESHOOTING TOUCH TEST CHART: TO SERVICE REVERSING VALVES