Carrier SUPRA 850Mt - Refrigeration Component Descriptions

2-27
Th
e
va
lv
e
MH
V1
is
a
va
lv
e
no
rm
al
ly
op
en
ed
meaning that the gas goes through when solenoid is
de-energized. In contrary with MHV2 which is a valve
normally closed.
MHV1 and MHV2 are energized then hot gas goes
through MHV2 to the serpentine, coil or evaporator.
2.
9.
3
Ho
t
Ga
s
V
al
ve
s
HG
V
1,
2
&
3
(N
C)
Liquid Suction Valves LSV 1, 2 & 3 (NC)
Figure 2-10
Hot gas & Liquid Suction Valv
es -
- NC
Description
Each evaporator has one Hot Gas Valve and one
Liquid Suction Valve.
During heati
ng, the
HGV opens and the LSV
closes
to allow hot gas to circulate in the evaporator coil.
During cooling, the LSV opens and the HGV closes
to allow liquid into the Expansion valve.
2.
9.
4
Ac
cu
mu
la
to
r
To evaporator
From c
onden
ser
Oil return orifice
To condensor
From evaporator
Figure 2-
11
Accum
ulator
The
acc
umu
lato
r
is
a
refri
ger
ant
hol
din
g
tanklocate
d
in
th
e
su
ct
io
n
li
ne
be
tw
ee
n
th
e
ev
ap
or
at
or
an
d
com
pre
sso
r.
The
pur
pos
e
of
the accum
ula
tor
is
to
prevent or minimize entry of any liquid refrigerant (that
ma
y
be
e
nt
ra
i
ne
d
in
th
e
su
ct
io
n
li
n
e)
in
to
th
e
compressor, causing internal damage.
This is accomplished by the compressor drawing the
re
fr
ig
er
a
nt
va
po
r
th
ro
ug
h
th
e
ou
tl
et
pi
pe
of
th
e
acc
um
ul
ato
r,
wh
ich
is
eq
ui
pp
ed
wit
h
an
ori
fic
e.
Thi
s
ori
fic
e
con
trols the oi
l return to
the com
pres
sor
and pre
ven
ts
the
accumulation of oil within the accumulator tank.
2.9
.5
By-
-pass
val
ve
(NC
)
(Su
pra
850
Mt
only)
Figure 2-12
By-
-pass valves
-
- NC
The valve is controlled by the micro (MPP2). The
valve opens and closes at the values chosen by FN6
(see Table 1--4 “ Bypass Valve setup” ).
The valve is energised during pull--down if the suc-
ti
on
pr
es
su
re
is
be
lo
w
th
e
va
lu
e
ch
os
en
by
FN
6
(de
faul
t=
1.17
bar
s).
If
the
pre
ssu
re
rise
s
abo
ve
the
value chosen by FN6 (default= 1.72bars) the valve is
de-
-energise
d.
The
valve
is
de-
-energised
durin
g
regula
-
tion in low speed heat, starting
,
cool and null ( see figu-
res 2.14 to 2.17).
2.
9.
6
Li
qu
id
si
gh
tg
la
ss
Dry
Wet
Sight glass, liquid indicator
Sight glass, moisture indicator
Th
is
co
mp
on
en
t
is
pl
ac
ed
on
the
rec
ei
ve
r
an
d
indicates :
-
-
Quickly th
e amou
nt of refrig
erant in
the
circuit. Permanent formation of
refrigera
nt
bubbl
es through t
he sightglass in
coolin
g
mode
indicates a lack of refrigerant charge.