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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.
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.
TABLE 6
M d l
Valve Field Size
Connections
Recommended Line Set
Model
Liquid
Line
Vapor
Line
Liquid
Line
Vapor
Line
L15
Line Sets
−024,−
036
3/8 in.
10 mm
7/8 in.
22 mm
3/8 in.
10 mm
7/8 in.
19 mm
L15−65
15 ft. − 50 ft.
4.6 m − 15 m
−048
3/8 in.
10 mm
1−1/8 in.
29 mm
3/8 in.
10 mm
7/8 in.
22 mm
L15−65
15 ft. − 50 ft.
4.6 m − 15 m
−060
3/8 in.
10 mm
1−1/8 in.
29 mm
3/8 in.
10 mm
1−1/8 in.
29 mm
Field
Fabricated
HPXA16 COOLING CYCLE
(Showing Gauge Manifold Connections)
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.
OUTDOOR
COIL
EXPANSION/
CHECK VALVE
BIFLOW
FILTER / DRIER
TO
R−410A
DRUM
LOW
PRESSURE
HIGH
PRESSURE
COMPRESSOR
REVERSING VALVE
VAPOR
LINE
VALVE
MUFFLER
NOTE − ARROWS INDICATE
DIRECTION OF REFRIGERANT FLOW.
REFRIGERANT WILL FLOW IN OPPOSITE
DIRECTION IN HEATING CYCLE.
SERVICE
PORT
SUCTION
EXPANSION/CHECK
VALVE
INDOOR UNIT
OUTDOOR UNIT
LIQUID
LINE
SERVICE
PORT
GAUGE MANIFOLD
DISTRIBUTOR
INDOOR
COIL
FIGURE 17
