Carrier SUPRA 750Mt - Unit runs but has insufficient cooling

4-14
2.
V
eri
fy
co
il
typ
e,
vo
lta
ge
an
d
fre
qu
en
cy
of
ol
d
an
d
ne
w
coil. This information appears on the coil housing.
3.
Pla
ce
new coil
ove
r
enc
los
ing tube, retain
er
and
connect wiring.
c.
Rep
lac
ing
sole
noid
val
ve
inte
rna
l
par
ts
(se
e
Figure 4-9)
1.
Pump down the u
nit. Frontseat bo
th service va
lves
to isolate the compressor.
2.
Remove
coil.
3.
Remove enclo
sing tube collar (item 4,
Figure
4-9)
usi
ng
ins
tall
atio
n/re
mov
al
toolsuppl
ied
with
rep
air
kit
(item 3).
4.
Ch
ec
k
pl
un
ge
r
for
res
tri
cti
on
du
e
to: (a
)
Co
rro
de
d
or
worn parts; (b) Foreign material lodged in valve; (c)
Bent or dented enclosing tube.
5.
Install new pa
rts. Do not overtighte
n enclosin
g tube
assembly. Torque to a value of 100 inch pounds
(1.15 mkg).
6.
Remove supplie
d
install
ation/re
moval tool.
Install
coil, voltage plate.
7.
Evacua
te and dehydrate the comp
ressor
. (Refer to
section 4.7)
8.
Star
t
uni
t
and chec
k
unl
oad
er opera
tion (Refe
r
to
section 4.11.a.).
1.
Coi
l
asse
mb
ly
2.
Installation
/removal
tool
3.
Enclo
sing
tub
e
Col
lar
4.
“O
”r
in
g
5.
Enc
los
in
g
tub
e
6.
Plun
ger
sprin
g
7.
Plun
ger
assem
bly
8.
Ga
sk
et
9.
V
alv
e
bo
dy
10
.
Ga
ske
t
1
1.
Bo
lt
12
.
Gas
ket
,
bo
lt
13
.
Pis
ton
rin
g
2.
3.
4.
5.
6.
7.
8.
9.
10.
11
.
12.
13.
1.
Figure 4-9
Unloader
solenoid va
lve
4.12
CHEC
KING
AND
REPLA
CING
FILTER-DRIER
2 methods
To Check Filter-Drier
-
-
Check fo
r a restricte
d or plu
gged fi
lter-drie
r
by feeling the liquid line inlet and outlet connec-
tions of the drier cartridge. If the outlet side
feels cooler than the inlet side, then the filter-
drier should be changed.
-
-
Inspect liq
uid sigh
tglass hu
midity in
dicator
.
To Replace Filter-Drier
a.
Pump down the uni
t per section 4.5.
Remove bracket, then replace drier.
b.
Check refrigerant level. (Refer to section 4.8.2)
4.13
CHEC
KING
AND
REPLA
CING
HIGH
PRESSURE CUTOUT SWITCH
4.1
3.1
Rep
lac
ing
high
pre
ssur
e
swi
tch
a.
Pu
mp
do
wn
theunit
(Re
fer
to
se
cti
on
4.5
).
Fro
nts
ea
t
both suction and discharge service valves to isolate
compressor (HP) or discharge and receiver valve
(BP).
b.
 Slowly
 rele
ase
compre
ssor
pressu
re
throug
h
the
service valve gauge ports.
c.
Disconnect wiring from defective switch. The high
pr
es
su
re
sw
it
ch
is
lo
ca
te
d
ne
ar
th
e
to
p
of
th
e
compre
ssor
. Low pressure swi
tch
on compre
ssor
or
suction line.
d.
 In
sta
ll
ne
w
cu
tou
t
sw
itc
h
aft
er
ve
rif
yi
ng
sw
itc
h
settings. (Refer to section 4.13.2)
e.
Evacua
te and
dehyd
rate the compressor
.
(Refer to
sectio
n
4.7)
4.1
3.2
Che
cki
ng
high
pre
ssur
e
swi
tch
WARNING
Do not use a
nitr
ogen cyl
inde
r
wit
hout
a
pr
e
s
s
ur
e
r
e
gu
l
a
t
or
.
C
y
l
in
de
r
pressur
e
is
approxi
matel
y
165 kg/cm
@
(2350 psi). Do not use oxygen in or
ne
ar
a
re
fr
ig
er
an
t
s
ys
te
m
as
a
n
expl
osio
n
mayoccur
(se
e
Figur
e
4-1
0).