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M−Start Capacitor (C7) −024 model only
All 2 ton HPXA16 units are equipped with a start capacitor
(C7). The capacitor is located in the control box and wired
in parallel with the compressor side of the dual capacitor.
C7 is de−energized by potential relay K31 when the com-
pressor nears full speed.
N−Potential Relay (K31) −024 model only
All 2 ton HPXA16 units are equipped with potential relay
K31, which controls the operation of the starting circuit. The
relay is located inside the control box and is normally
closed when contactor K1 is de−energized. When K1 is en-
ergized the compressor begins start up. K31 remains
closed closed during start up and capacitor C7 remains in
the circuit. When the compressor reaches 75% of its
speed, K31 is energized, de−energizing capacitor C7.
O−High Pressure Switch (S4)
An auto-reset, single-pole/single-throw high pressure switch
is located in the liquid line. This switch shuts off the compres-
sor when liquid line pressure rises above the factory setting.
The switch is normally closed and is permanently adjusted to
trip (open) at 590 + 10 psi and close at 418 + 10 psi. See fig-
ure 10 for switch location.
P−Reversing Valve (L1)
A refrigerant reversing valve with an electromechanical so-
lenoid is used to reverse refrigerant flow during unit opera-
tion. The reversing valve is energized during cooling de-
mand and during defrost.
EXPANSION/
CHECK VALVE
LOW
HIGH
PRESSURE
PRESSURE
GAUGE MANIFOLD
TO
R−410A
DRUM
NOTE−Use gauge ports on vapor line valve and liquid valve for evacuating refrigerant lines
and indoor coil. Use suction gauge port to measure suction pressure during charging.
HPXA16 COOLING CYCLE
(Showing Gauge Manifold Connections)
DISTRIBUTOR
BIFLOW
OUTDOOR
FILTER / DRIER
MUFFLER
LIQUID
LINE
SERVICE
PORT
III−REFRIGERANT SYSTEM
Field refrigerant piping consists of liquid and vapor lines
from the outdoor unit (sweat connections). Use Lennox
L15 series line sets as shown in table 6.
Separate liquid and suction service ports are provided at
the service valves for connection of gauge manifold during
charging procedure. Figure 17 shows HPXA16 refrigerant
flow and gauge manifold connections.
Valve Field Size
Connections
Model
M d l
Liquid
Line
−024,−
3/8 in.
036
10 mm
3/8 in.
−048
10 mm
3/8 in.
−060
10 mm
OUTDOOR UNIT
REVERSING VALVE
COIL
SUCTION
SERVICE
PORT
COMPRESSOR
FIGURE 17
Page 14
TABLE 6
Recommended Line Set
Vapor
Liquid
Vapor
Line
Line
Line
7/8 in.
3/8 in.
7/8 in.
22 mm
10 mm
19 mm
3/8 in.
7/8 in.
1−1/8 in.
10 mm
22 mm
29 mm
1−1/8 in.
3/8 in.
1−1/8 in.
29 mm
10 mm
29 mm
NOTE − ARROWS INDICATE
DIRECTION OF REFRIGERANT FLOW.
REFRIGERANT WILL FLOW IN OPPOSITE
DIRECTION IN HEATING CYCLE.
INDOOR UNIT
VAPOR
LINE
VALVE
INDOOR
EXPANSION/CHECK
VALVE
L15
Line Sets
L15−65
15 ft. − 50 ft.
4.6 m − 15 m
L15−65
15 ft. − 50 ft.
4.6 m − 15 m
Field
Fabricated
COIL
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