Air Evacuation - Midea MFYA400-24HRFN8-QRD0W User Manual

Air Evacuation

NOTE
When opening valve stems, turn the hexagonal wrench until it hits against the stopper. Do not try to
force the valve to open further.
Preparations and precautions
Air and foreign matter in the refrigerant circuit
can cause abnormal rises in pressure, which can
damage the air conditioner, reduce its e ciency,
and cause injury. Use a vacuum pump and manifold
gauge to evacuate the refrigerant circuit, removing
any non-condensable gas and moisture from the
system. Evacuation should be performed upon
initial installation and when unit is relocated.
Evacuation Instructions
1. Connect the charge hose of the manifold gauge
to 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 Meter reads -76cmHG(-10 Pa).
Outdoor unit
Compound
pressure
Pressure hose
Charge hose
Low pressure
5
Manifold
Gauge
-76cmHg
Pressure
gauge gauge
Low
High
pressure
valve
valve
or
Charge
hose
valve
Close the Low Pressure side of the manifold
6.
gauge, and turn o the vacuum pump.
7. Wait for 5 minutes, then check that there
has been no change in system pressure.
8. If there is a change in system pressure, refer
to Gas Leak Check section for information
on how to check for leaks. If there is no
change in system pressure, unscrew the cap
from the packed valve (high pressure valve).
9. Insert hexagonal wrench into the packed valve
(high pressure valve) and open the valve by
turning the wrench in a 1/4 counterclockwise
turn. Listen for gas to exit the system, then
close the valve after 5 seconds.
10. Watch the Pressure Gauge for one minute
to make sure that there is no change in
pressure. The Pressure Gauge should read
slightly higher than atmospheric pressure.
11. Remove the charge hose from the service port.
valve body
12. Using hexagonal wrench, fully open both the
high pressure and low pressure valves.
13. Tighten valve caps on all three valves (service
port, high pressure, low pressure) by hand.
You may tighten it further using a torque
wrench if needed.
Vacuum
pump
25
Flare nut
Cap
valve stem