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Troubleshooting Touch Test Chart: To Service Reversing Valves
MALFUNCTION OF VALVE
No voltage to coil.
Defective coil.
Low charge.
Pressure differential too high.
Pilot valve okay. Dirt in one
bleeder hole.
Piston cup leak
Hot
Hot
Warm
Hot
Hot
Hot
Hot
Hot
Hot
Hot
Hot
Hot
Hot
Warm
Cool
Cool
Cool
Warm
Warm
Hot
Hot
Cool
Cool
Cool
Cool
Cool
Cool
Cool
Raise head pressure, operate solenoid to free.
If still no shift, replace valve.
Raise head pressure, operate solenoid to free
partially clogged port. If still no shift, replace
valve.
Replace compressor
Check unit for correct operating pressures and
charge. Raise head pressure. If no shift, use
valve with smaller port.
Replace valve
Raise head pressure, operate solenoid. If no
shift, replace valve.
Replace valve
Raise head pressure, operate solenoid. If no
shift, use valve with smaller ports.
Raise head pressure, operate solenoid. If no
shift, replace valve.
Operate valve several times, then recheck. If
excessive leak, replace valve.
Operate valve several times, then recheck. If
excessive leak, replace valve.
Stop unit. Will reverse during equalization
period. Recheck system
Raise head pressure, operate solenoid to free
dirt. If still no shift, replace valve.
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.
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.
Replace valve.
Replace compressor
Repair electrical circuit.
Replace coil.
Repair leak, recharge system.
Recheck system.
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.
Stop unit. After pressures equalize, restart with
solenoid energized. If valve shifts, reattempt
with compressor running. If still no shift, replace
valve.
Check Electrical circuit and coil
Check refrigeration charge
Hot
Cool
Cool,
as (2)
*TVB
Hot
Hot,
as (1)
SUCTION TUBE
to Compressor
Valve will
not shift
from cool to
heat.
Valve will
not shift
from cool to
heat.
Starts to
shift but
does not
complete
reversal.
Will not shift
from heat to
cool.
Apparent
leap in
heating.
Clogged pilot tubes.
Both ports of pilot open. (Back seat
port did not close).
Defective Compressor.
Not enough pressure differential at
start of stroke or not enough flow to
maintain pressure differential.
Body damage.
Both ports of pilot open.
Body damage.
Valve hung up at mid-stroke. Pumping
volume of compressor not sufficient to
maintain reversal.
Both ports of pilot open.
Piston needle on end of slide leaking.
Pilot needle and piston needle leaking.
Pressure differential too high.
Clogged pilot tube.
Dirt in bleeder hole.
Piston cup leak.
Defective pilot.
Defective compressor.
*TVB
Hot
Warm
Hot
Hot
Hot
Hot
*TVB
**
WVB
*TVB
*TVB
*TVB
Hot
*TVB
NORMAL FUNCTION OF VALVE
DISCHARGE TUBE
from Compressor
Tube to INSIDE
COIL
Tube to OUTSIDE
COIL
LEFT Pilot
Capillary Tube
RIGHT Pilot
Capillary Tube
VALVE
OPERATING
CONDITION
*TVB
Hot
*TVB
*TVB
Hot
*TVB
Hot
*TVB
**
WVB
*TVB
Hot
Hot
Hot
Warm
Hot,
as (1)
Hot,
as (1)
Warm,
as (1)
Hot
Hot
Hot
Hot
Cool,
as (2)
Cool,
as (2)
Cool,
as (2)
Cool,
as (2)
Cool,
as (2)
Cool,
as (2)
Cool,
as (2)
Cool,
as (2)
Cool,
as (2)
Cool,
as (2)
Warm
Warm
Hot
Hot,
Hot,
as (1)
Hot,
as (1)
Hot,
as (1)
Hot,
as (1)
Hot,
as (1)
Hot,
as (1)
Warm,
as (1)
NOTES:
* TEMPERATURE OF VALVE BODY
** WARMER THAN VALVE BODY
1 2 3 4 5 6 POSSIBLE CAUSES CORRECTIONS
Normal Hot Cool Cool Hot *TVB TVB
Cooling as (2) as (1)
Normal Heating Hot Cool Hot Cool *TVB TVB
as (1) as (2)