Pioneer YN-M Series Installation Manual page 20

1. Completely tighten ALL brass flare nuts, which
connect the ends of copper refrigerant lines to the
attached indoor units and the circuit service valves
on the outdoor unit, using proper torque.
2. Ensure that both the 2-way (Liquid) and 3-way
(Gas) valves for each circuit at the outdoor unit
STAY CLOSED, just as they arrived originally.
3. Connect the low pressure hose on your gauge
manifold (usually blue) to the 3-way (Gas) valve's
service port, belonging to circuit A. Note: If there
is only one indoor unit, it should be attached to
circuit A as the primary.
4. If the manifold gauge set's hoses have 1/4" SAE
connections, a 1/4" to 5/16" SAE port adapter will
be needed. (Sold separately).
5. Connect the center hose of the gauge manifold
(usually yellow) to the vacuum pump.
6. Fully open the gauge manifold valve on the low
side (blue) of your gauge manifold. Ensure that the
manifold valve on the high side (red) of your
manifold gauge stays closed.
7. Start the vacuum pump, and operate according
to the pump manufacturer's specifications. If your
vacuum pump has a valve, open it as well.
8. If the proper vacuum cannot be achieved within
30 minutes, the vacuum pump should be kept
running for an additional 15 minutes. If, after the
additional 15 minutes of operation, the vacuum
still cannot be achieved, there could be a leak at
one or more of the flare pipe connections at either
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end of the refrigerant pipes. The leak must be located,
and the leaking nut must be tightened properly,
before re-vacuuming the circuit.
9. If the vacuum is achieved, close the manifold valve
at the low (blue) side on your gauge manifold first,
and shut the vacuum pump off. Leave the gauge
manifold set and the hoses connected, and recheck
the vacuum reading 15 minutes later to ensure there
is no vacuum loss. (Very small increases in vacuum
level is normal).
10. Circuit A is now dry and free of contaminants.
Do not remove the hose of your gauge manifold set
from the service port.
11. Remove the 2-way (liquid) service valve's brass cap
of circuit A. Insert proper size Allen wrench into the
valve core, turn it counter-clockwise for 1/4 turn,
wait for 5 seconds, and quickly close the valve by
turning it in reverse direction. Check your low pressure
gauge on the manifold to be sure it now indicates
positive pressure of approximately 80 to 120 PSI in
your lines.
Flare nut
Valve body Valve stem
12. Apply soap-water mixture on both the indoor unit
connections and the outdoor unit connections for
circuit A with a soft brush to check for leakage at the
connecting points of the piping. If you notice air
bubbles, the specific connector has leakage and must
be tightened to stop the leakage. (An electronic leak
detector will be more efficient to use, if available).
13. Re-insert the proper size Allen wrench into the valve
core of the 2-way (liquid) circuit valve for circuit A, and
turn it counter-clockwise until it is fully back seated.
Do not force it, once it stops turning. Repeat the leak
checking procedure entirely at all connections of
circuit A. If you find a new leak, close the 2-way (liquid)
circuit valve you just opened first, and tighten the flare
nut at the leaking connection, until the leak is sealed.
Reopen the 2-way (liquid) valve, and check again.
14. Remove the 3-way (gas) service valve's cap for circuit
A. Insert proper size Allen wrench into the valve core,
and turn it counter clockwise until it is fully back seated.
Do not force it, once it stops turning.
2-way (Liquid)
Service Valve
Cap