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Fixed Orifice Systems
SCU12M units are shipped with a fixed orifice refrigerant
metering device. Replace the existing indoor unit fixed
orifice with the orifice supplied with this unit. Place the
supplied fixed orifice sticker on the indoor cabinet after
installation. See Table 2 for the proper fixed orifice size for
each unit. In nonstandard applications, the provided fixed
orifice may not be appropriately sized.
Install the fixed orifice as shown in Figure 4. Do not twist
cap tubes when loosening the seal nut from the orifice
housing.
Fixed Orifice Sizes
M
o
d
l e
S
C
U
1
2
M
0 -
2
4
S
C
U
1
2
M
0 -
3
0
S
C
U
1
2
M
0 -
3
6
S
C
U
1
2
M
0 -
4
2
S
C
U
1
2
M
0 -
4
8
S
C
U
1
2
M
0 -
6
0
Table 2
Expansion Valve Systems
Expansion valves equipped with Chatleff-type fittings are
available from the manufacturer. To install a thermo
extension valve (see Figure 4):
1. Insert suction line splice between evaporator and
suction line with the equalizer port pointing upwards.
To prevent plugging the equalizer line with oil, the
equalizer port must be between a 10:00 and 2:00
position.
2. Separate the distributor assembly and remove the
piston orifice and used teflon seal. Insert nozzle end of
the thermo expansion valve along with a new teflon seal
into the distributor and tighten to 20 – 30 ft. lbs. Use
backup wrench on all wrench flats. Overtightening will
crush the teflon seal and may cause a leak.
3. Attach liquid line portion of distributor assembly along
with new teflon seal to the inlet of the thermo expan-
sion valve. Tighten to 20 – 30 ft. lbs. Use backup
wrench on all wrench flats. Overtightening will
crush the teflon seal and may cause a leak.
# 504,910M
F
x i
e
d
O
r
f i
c i
e
S
z i
e
0 .
6
3
0 .
6
3
0 .
7
1
0 .
7
8
0 .
8
1
0 .
9
0
Metering Device Installation
Figure 4
4. Connect the external equalizer line to the equalizer
port on the suction line splice.
5. Strap the superheat sensing bulb to the suction header.
If installing an expansion valve on an indoor coil that
previously used a fixed orifice, be sure to remove the
existing fixed orifice. Failure to remove a fixed orifice
when installing an expansion valve to the indoor coil will
result in improper operation and damage to the system.
Manifold Gauge Set
Manifold gauge sets used with systems charged with
R410A refrigerant must be capable of handling the higher
system operating pressures. The gauges should be rated
for use with pressures 0 – 800 on the high side and a low
side of 30" vacuum to 250 psi with dampened speed to
500 psi. Gauge hoses must be rated for use at up to 800
psi of pressure with a 4000 psi burst rating.
Liquid and Suction Line Service Valves
The liquid line and suction line service valves (see Figure
5 on page 8) and gauge ports are accessible from inside
the unit, behind the access panel. The service ports are
used for leak testing, evacuating, charging, and checking
charge. See Table 3 on page 8 for torque requirements.
Each valve is equipped with a service port which has a
factory-installed Schrader valve. A service port cap
protects the schrader valve from contamination and
serves as the primary leak seal.
To Access the Schrader Port:
1. Remove the access panel.
2. Remove the service port cap with an adjustable wrench.
Page 7
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