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TROUBlESHOOTING TOUCH TEST CHART: TO SERVICE REVERSING VAlVES
VALVE
OPERATING
CONDITION
1
Normal Cooling
Hot
Normal Heating
Hot
Check Electrical circuit and coil
Check refrigeration charge
Valve will not
shift from cool
Hot
to heat.
Hot
Valve will not
shift from cool
Hot
to heat.
Warm
Hot
Starts to shift
Hot
but does not
complete
H
t o
reversal.
Hot
Apparent
Hot
leap in heat-
ing.
Hot
Hot
Hot
Will not shift
from heat to
cool.
Hot
14
Hot
Warm
NORMAL FUNCTION OF VALVE
2
3
4
5
Cool
Hot
Cool
*TVB
as (2)
as (1)
Hot
Cool
Cool
*TVB
as (1)
as (2)
MALFUNCTION OF VALVE
Cool,
Hot,
Cool
*TVB
as (2)
as (1)
Cool,
Hot,
Cool
*TVB
as (2)
as (1)
Cool,
Hot,
Cool
Hot
as (2)
as (1)
Cool,
Hot,
Cool
*TVB
as (2)
as (1)
Warm
Warm
Hot
*TVB
Warm
Warm
Hot
Hot
H
t o
H
t o
H
t o
T *
V
B
Hot
Hot
Hot
Hot
Hot,
Cool,
Cool
*TVB
as (1)
as (2)
Hot,
Cool,
Cool
**WVB
as (1)
as (2)
Hot,
Cool,
Cool
*TVB
as (1)
as (2)
Hot,
Cool,
Cool
Hot
as (1)
as (2)
Hot,
Cool,
Cool
Hot
as (1)
as (2)
Hot,
Cool,
Cool
H
t o
as (1)
as (2)
Warm,
Cool,
Cool
Warm
as (1)
as (2)
* TEMPERATURE OF VALVE BODY
** WARMER THAN VALVE BODY
6
POSSIBLE CAUSES
TVB
TVB
N
o
v
l o
a t
g
e
o t
c
o
. l i
D
e
e f
c
v i t
e
c
o
. l i
L
o
w
c
h
a
g r
. e
Pressure differential too high.
Hot
Pilot valve okay. Dirt in one bleeder hole.
Piston cup leak
*TVB
Clogged pilot tubes.
Both ports of pilot open. (Back seat port
Hot
did not close).
Warm
Defective Compressor.
Not enough pressure differential at start
Hot
of stroke or not enough fl ow to maintain
pressure differential.
B
o
d
y
d
a
m
a
g
. e
Hot
Both ports of pilot open.
H
t o
B
o
d
y
d
a
m
a
g
. e
Valve hung up at mid-stroke. Pumping
volume of compressor not suffi cient to
maintain reversal.
Hot
Both ports of pilot open.
*TVB
Piston needle on end of slide leaking.
**WVB
Pilot needle and piston needle leaking.
*TVB
Pressure differential too high.
Clogged pilot tube.
*TVB
Dirt in bleeder hole.
*TVB
Piston cup leak.
H
t o
D
e
e f
c
v i t
e
p
o l i
. t
*TVB
Defective compressor.
NOTES:
CORRECTIONS
R
e
p
a
r i
e
e l
c
r t
c i
l a
i c
c r
u
. t i
R
e
p
a l
c
e
c
o
. l i
R
e
p
a
r i
e l
a
, k
e r
c
h
a
g r
e
s
s y
e t
m
.
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.
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.
R
e
p
a l
c
e
v
a
v l
e
Raise head pressure, operate solenoid. If
no shift, use valve with smaller ports.
R
e
p
a l
c
e
v
a
v l
e
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.
R
e
p
a l
c
e
v
a
v l
. e
Replace compressor
39
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