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8
Air Evacuation & Adding Refrigerant
Preparations & Precautions
Air and foreign matter in the refrigerant circuit can
cause abnormal rises in pressure, which can damage
the system, reduce its efficiency, and/or cause
personal injury. Use a vacuum pump and manifold
gauge to evacuate the refrigerant circuit and remove
any incondensable gas and moisture from the
system. NOTE: Evacuation should be performed
upon initial installation or when the unit
is relocated.
Before using the manifold gauge and vacuum pump,
read their operation manuals to familiarize yourself
with how to use them properly.
1. Connect the charge hose of the manifold gauge
to the service port on the outdoor unit’s low
pressure valve.
2. Connect another charge hose from the manifold
gauge to the vacuum pump.
3. Open the low pressure side of the manifold gauge.
Keep the high pressure side closed.
4. Turn on the vacuum pump to evacuate the system.
5. Run the vacuum for at least 15 minutes, or until the
compound gauge reads -76 cmHG (-10
5
Pa).
BEFORE PERFORMING EVACUATION
Check to make sure the refrigerant piping
between the indoor and outdoor unit is
connected properly and in accordance with
the Refrigerant Piping Connection section
of this manual.
Ensure all wiring is properly connected in
accordance with all local & national
electrical codes and the wiring diagram
located on the back of the outdoor
condenser wiring cover .
Evacuation Instructions
Manifold Gauge
Compound gauge
-76 cmHg (10
5
Pa)
Low pressure valve
High pressure
valve
Pressure hose/
Charge hose
Charge
hose
Vacuum
pump
Pressure gauge
Low pressure valve
6. Close the low pressure side of the manifold gauge,
and turn off the vacuum pump.
7. Wait for a duration of 5 minutes, then check that
there has been no change in system pressure.
8. If there is a change in system pressure, refer to the
Gas Leak Checks section of this manual for more
detailed information on how to check the piping
and connections for leaks. If there is no change in
system pressure, unscrew the cap from the packed
valve (high pressure valve).
9. Insert an Allen/hexagonal wrench into the packed
valve (high pressure valve) and open the valve by
turning the wrench 1/4 turn counter-clockwise
(Refer to Fig. 8.1). Listen for gas to exit the system,
then close the valve after 5 seconds. If installing a
3, 4, or 5 zone multi-zone condenser, open all
of the high pressure valves connected to the
air handler piping 1/4 turn counter-clockwise
first. Now, open the high pressure main valve
1/4 turn counter-clockwise. Listen for gas to
exit the system, then close the main valve
after 5 seconds. Then, close all of the other
valves. Refer to Fig. 8.2.
Flare nut
Cap
Valve body
Valve stem
Fig. 8.1
Fig. 8.2
Low
Pressure
Main Valve
High
Pressure
Main Valve
“Liquid”
High
Pressure
“Suction”
Low
Pressure
Wrench
Air Handler
Connection
Valves
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