Carrier SUPRA 950Mt - Evacuation and Dehydration

4-10
c.
 Remo
ve
refri
ger
ant
usi
ng
a
refr
ige
rant
reco
very
sy
st
em
an
d
re
pa
ir
an
y
le
ak
s.
Ev
ac
ua
te
an
d
de
hy
dra
te
the
un
it.
(Re
fe
r
to
se
cti
on4.7)
Ch
ar
ge
un
it
with refri-gerant. (Refer to section 4.8 )
4.7
EV
ACU
A
TION
AND
DEHY
DRA
TION
4
.7
.1
G
e
ne
r
a
l
Moi
stur
e
is
the
dea
dly
ene
my
of
refri
ger
ant
sys
tems
.
The presence of
moistu
re in
a refrigeration system can
have many undesirable effects. The most common are
copper plating, acid sludge formation, “freezing-up” of
metering devices by free water, and formation of acids,
resulting in metal corrosion.
4.
7.
2
Pr
ep
ar
at
io
n
a.
Eva
cua
te
and dehyd
rate only
afte
r
pre
ssu
re
lea
k
test. (Refer to section 4.6)
b.
Essential tools to properly evacuate and dehydrate
any system include a good vacuum pump (5 cfm =
8m
#
H volume displacement, P/N 07-00176-01) and
a good vacuum indicator such as a thermocouple
vacuum gauge (vacuum indicator).
NOTE
It
is
not
reco
mme
nde
d
usi
ng a
com
pou
nd
gau
ge
because of its inherent inaccuracy.
c.
 Ke
ep
the
amb
ien
t
tem
pera
ture
abo
ve
15.
6
_
C(60
_
F)
to
sp
ee
d
ev
ap
or
at
io
n
of
mo
is
tu
re
.
If
am
bi
en
t
temperature is lower than 15.6
_
C (60
_
F), ice might
form
bef
ore
moi
stur
e
rem
ova
l
is
com
ple
te.
Hea
t
lamps or alternate sources of heat may be used to
raise system
tempera
ture.
4.
7.
3
Pr
oc
edu
re
for
Ev
ac
uat
ion
an
d
Dehydrating system
a.
 Remo
ve
refri
ger
ant
usi
ng
a
refr
ige
rant
reco
very
system.
b.
Th
e
re
co
mm
en
de
d
me
th
od
to
ev
ac
ua
te
an
d
deh
ydr
ate
the
sys
tem
is
to
con
nec
t
thre
e
eva
cua
tion
hoses (Do not use standard service hoses, as they
ar
e
no
t
su
ite
d
for
ev
ac
ua
tio
n
pu
rp
os
es
.)
as
sh
ow
n
in
Fig
ure 4
-7
to
the
vac
uum
pum
p
and refrige
rati
on
uni
t.
Also
,
as
sho
wn,
con
nec
t
a
eva
cua
tionmanifo
ld,
with evacuation hoses only, to the vacuum pump,
electronic vacuum gauge, and refrigerant recovery
system.
c.
 With the unit service valves closed (back seated)
and
the
vac
uum
pum
p
and
ele
ctro
nic
vac
uum
gau
ge
va
lv
es
op
en
,
st
ar
t
th
e
pu
mp
an
d
dr
aw
a
de
ep
vacuum. Shut off the pump and check to see if the
va
cu
um
ho
ld
s.
Th
is
op
er
a
ti
o
n
is
to
te
st
th
e
evacuation setup for leaks, repair if necessary.
d.
Midse
at the
refrige
rant system service valves.
e.
The
n
ope
n
the
vac
uum
pum
p
and
ele
ctro
nic
vac
uum
gauge valves, if they are not already open. Start the
vac
uum
pum
p.
Evac
uat
e
uni
t
unt
il
the
ele
ctro
nic
vacuum gauge indicates 2000 microns. Close the
ele
ctro
nic
vac
uum
gau
ge
and
vac
uum
pum
p
val
ves
.
Sh
ut
of
f
the
va
cu
um
pu
mp
.
W
ai
t
a
few
mi
nu
tes
to
be
sure the vacuum holds.
f.
Brea
k
the vacuu
m
with clea
n
dry refrige
ran
t.
Use
re
fri
ge
ran
t
tha
t
the
un
it
ca
ll
s
for
.
Ra
is
e
sy
ste
m
pressu
re t
o approximate
ly
2
psig.
g.
 Re
mov
e
refr
ige
ran
t
usi
ng
a
refri
ger
ant
rec
ove
ry
system.
h.
 Repeat steps
e.
 through
g.
one time.
i.
Eva
cua
te
uni
t
to
500 micro
ns. Close off
vac
uum
pu
mp
va
lv
e
an
d
st
op
pu
mp
.
W
ai
t
fi
ve
mi
nu
te
s
to
se
e
if vacuum holds. This checks for residual moisture
and/or leaks.
j.
With
a
vac
uum
stil
l
in
the
uni
t,
the
refri
gera
nt
cha
rge
may be drawn into the system from a refrigerant
container on weight scales. The correct amount of
refrigerant may be added by observing the scales.
(Refer to section 4.8)