Kga/Kca 090 Charging Curves; Compressor Controls; Freezestat; High Pressure Switch - Lennox KGB024 Installation Instructions Manual

130
120
110
100
90
80
70
60
100 110
F-Compressor Controls
See unit wiring diagram to determine which controls are
used on each unit. Optional controls are identified on
wiring diagrams by arrows at junction points.
1- Freezestat (S49)
Switch de-energizes compressor when evaporator
coil temperature falls below 29°F (-2°C) to prevent
evaporator freeze-up.
evaporator coil temperature reaches 58°F (15°C).
2- High Pressure Switch (S4)
High pressure switches are SPST N.C. switches
which open on a pressure rise. The switch is a
manual reset switch on KGA/KCA036, 048, 060 &
090 units. The switch is an auto-reset switch on
KGB/KCB024-074 and KGA/KCA072 units.
KG/KC 024, 030, 036, 048, 060, 072, 074, 090

KGA/KCA 090 Charging Curves

120 130
Suction Pressure (psig)
Switch resets when
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Outdoor Temperature (°F)
65°
140 150
S4 is wired in series with the compressor contactor
coil and is located on the compressor discharge line.
When discharge pressure rises to 640+10psig
(4412+69kPa), indicating a problem with the system,
the switch opens. The respective compressor is
de-energized but the economizer can continue to
operate.
Auto-reset switches
(3275+138kPa)
3- Compressor High Temperature Limit (S5)
S5 is located on the top of Interlink compressors and
is wired in series with the high pressure switch S4.
115°
105°
95°
85°
75°
160 170
close at 475+20psig