Allied Air 4AC18LT Series, Installation And Maintenance Instructions Manual

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506469-01 Issue 1008
3. Connect the external equalizer line to the equalizer port
on the suction line and tighten to 8 ft.lbs.
4. 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 guage 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 1 - 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
11) and service ports are used for leak teating, evacuation,
charging, and checking charge.
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 service port cap with an adjustable wrench.
2. Connect gauge to the service port.
3. When testing is completed, replace service port cap.
Tighten finger tight, then an additional 1/6 turn.
To Open Liquid or Suction Line Service Valve:
Remove stem cap with an adjustable wrench.
Use service wrench with a hex-head extension to back the
stem out counterclockwise as far as it will go. Use a 3/16”
hex head extension for liquid line service valves and a 5/
16” extension for suction line service valves.
Replace the stem cap. Tighten finger tight, then tighten an
additional 1/6 turn.
To Close Liquid or Suction Line Service Valve:
1. Remove the stem cap with an adjustable wrench.
2. Use a service wrench with a hex-head extension to turn
the stem clockwise to seat the valve. Tighten firmly.
3. Replace the stem cap. Tighten finger tight, then tighten
an additional 1/6 turn.
Suction Line (Ball Type) Service Valve
Suction line (ball type) service valves function the same way
as the other valves; the difference is in the construction (See
Figure 12).
The ball valve is equipped with a service port with a factory-
installed Schrader valve. A service port cap protects the
Schrader valve from contamination and serves as the
primary seal.
Leak Testing
After the line set has been connected to the indoor and
outdoor units, the line set connections and indoor unit must
be checked for leaks.
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Figure 11