Pioneer YN-M Series Installation Manual page 21

Flare nut
Valve stem
Valve body
15. Power up the system, and run the indoor unit
for circuit A in COOLING mode to ensure that all
functions are working.
16. Switch the indoor unit of circuit A to HEAT
mode, and ensure that all functions are working.
17. Set temperature on remote to the HIGHEST
setting, and while the unit is running in heat
mode, check one last time for leaks on all 4
related pipe connections of circuit A. It is
easier to catch even the smallest leaks in HEAT
mode, as the pressures are much higher.
18. If you discover a leak that cannot be stopped
by tightening the flare nuts at this stage, shut off
both 2-way (liquid) and 3-way (gas) service valves,
repair the leak properly, and start from the
beginning. Please remember you may need to
add fresh refrigerant to the system, as a significant
value may have been lost at this stage.
19. REPEAT THIS ENTIRE PROCEDURE FOR
CIRCUIT B (if it is being utilized by an indoor unit).
PROCEDURE FOR 3, 4, AND 5 ZONE OUTDOOR
UNITS ARE DIFFERENT FROM 2 ZONE MODELS.
FOR 3, 4, AND 5 ZONE SYSTEMS:
Indoor units and the pipes between indoor and
outdoor units must be evacuated and leak tested to
remove trapped air and moisture from the system.
ONE CIRCUIT AT A TIME. This procedure should start
after all electrical connections are finalized, and the
system receives proper power for immediate test
running, to be performed one circuit at a time.
For installation convenience, one set of COMMON
(or MASTER) service valves have been adopted
into the 3, 4, and 5 zone systems. The common
(master) set of service valves control the common
refrigerant circuitry behind the standard sets of
circuit service valves, where the indoor units are
attached. See the layout shown in the next picture.
3-way (Gas) Valve
Cap
In some models, common (master) valves are on
the left side of the area of the circuit service valves.
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 sufficient torque.
2. Ensure that both of the 2-way (liquid) and 3-way
(gas) service valves for each circuit at the outdoor
unit STAY CLOSED as they arrived.
3. Connect the low pressure hose on your gauge
manifold (usually blue) to the 3-way (gas) service
valve's service port, belonging to circuit A.
COMMON (MASTER)
Service Valves
Circuit Service Valves
WARNING FOR 3, 4, 5 ZONE:
COMMON (MASTER) VALVES
MUST BE OPENED BEFORE
OPENING THE CIRCUIT
SERVICE VALVES. RUNNING
THE SYSTEM WHILE THE
MASTER VALVE SET IS CLOSED
WILL RESULT IN INSTANT
COMPRESSOR FAILURE!
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