Lennox KHA SERIES, Руководство пользователя

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Page 25
B−Cooling Components
If Interlink compressor replacement is necessary, call
1−800−4−LENNOX (1−800−453−6669).
IMPORTANT
Some scroll compressors have an internal vacuum
protector that will unload scrolls when suction
pressure goes below 20 psig. A hissing sound will
be heard when the compressor is running un-
loaded. Protector will reset when low pressure in
system rises above 40 psig. DO NOT REPLACE
COMPRESSOR.
KHA units use one cooling circuit consisting of a compres-
sor, outdoor coil and indoor coil. See figure 5. Units are
equipped with one draw−through type condenser fan. All
units are equipped with indoor blowers which draw air
across the indoor coil during unit operation. KHA units have
three condensate drain locations: front, back and bottom of
unit. See unit installation instructions for more detail.
Cooling may be supplemented by a factory or field-
installed economizer. The indoor coil is slab type. The in-
door coil uses a thermostatic check/expansion valve as the
primary expansion device. The indoor coil is also equipped
with enhanced fins and rifled tubing. In all units the compressor
is protected by a freezestat (S49) (on the indoor coil) and a
high pressure switch (S4). A low ambient switch (S84) is
available as an option for additional compressor protection.
1−Compressor B1
All KHA024/060 units use scroll compressor. See SPEC-
IFICATIONS" and ELECTRICAL DATA" (table of contents)
or compressor nameplate for compressor specifications.
WARNING
Electrical shock hazard. Compressor must be
grounded. Do not operate without protective cover
over terminals. Disconnect power before removing
protective cover. Discharge capacitors before servic-
ing unit. Failure to follow these precautions could
cause electrical shock resulting in injury or death.
The compressor is energized by a corresponding com-
pressor contactor.
NOTE−Refer to the wiring diagram section for specific unit
operation.
2−Freezestat S49
Each unit is equipped with a low temperature switch (freezes-
tat) located on the return bend of the indoor coil.
The freezestat is wired to LO PS" on the CMC1 board and is
a SPST N.C. auto−reset switch which opens at 29

F + 3

F
(-1.7

C + 1.7

C) on a temperature drop and closes at 58

F
+ 4

F (14.4

C + 2.2

C) on a temperature rise. To prevent
coil icing, the freezestat opens during compressor op-
eration to temporarily disable the compressor until the
coil warms sufficiently to melt any accumulated frost.
If the freezestat is tripping frequently due to coil icing, check the
airflow, filters and unit charge before allowing unit back in op-
eration. Make sure to eliminate conditions which might pro-
mote indoor coil ice buildup.
3−High Pressure Switch S4
The high pressure switch is an auto reset SPST N.C. switch
which opens on a pressure rise. The switch is located in the
compressor discharge line and is wired to HI PS" on the
CMC1 board.
When discharge pressure rises to 640 ± 10 psig (4413 ±
69 kPa) (indicating a problem in the system) the switch
opens and the CMC1 board de−energizes the compres-
sor (the economizer can continue to operate). S4 will
close when pressure drops back to 475 psig (3275 kPA).
4−Low Ambient Switch S11 (option)
The low ambient switch is an auto-reset SPST N.O. pres-
sure switch which allows for mechanical cooling opera-
tion at low outdoor temperatures. In all models a switch
is located in the liquid line prior to the indoor coil section.
In the P and Y voltage units S11 is wired in series with the K1
contactor and the CMC1 board fan contacts. In G, J and M volt-
age units S11 in series with outdoor fan relay K10 and low am-
bient relay K58 (if used).
When liquid pressure rises to 450 ± 10 psig (3102 ± 69
kPa), the switch closes and the condenser fan is ener-
gized. When discharge pressure in drops to 240 ± 10 psig
(1655 ± 69 kPa), the switch opens and the condenser fan in
that refrigerant circuit is de−energized. This intermittent fan
operation results in higher evaporating temperature allow-
ing the system to operate without icing the indoor coil and
losing capacity.
5−Reversing Valve L1
A refrigerant reversing valve with a 24 volt solenoid coil
is used to reverse refrigerant flow during unit operation
in all KHA units. The reversing valve is connected in the va-
por line of the refrigerant circuit. The reversing valve coil is
energized during cooling demand and during defrost.
Reversing valve L1 is controlled by the CMC1 board and
transfer relay K8 in response to cooling demand or by defrost.
6−Condenser Fan Motor B4
See specifications section of this manual for specifications of
condenser fan B4. B4 is energized by contactor K1 in P and Y
voltage units and K10 in G and J units. All motors are ball
bearing type single−phase motors. The fans may be removed
for servicing and cleaning by removing the fan grilles.
7−Low Temperature Switch S3 (option)
(compressor monitor)
S3 is a SPST bimetal thermostat which opens on tempera-
ture drop. It is wired in line with the indoor thermostat and
transfer relay K8. In the cooling mode, when outdoor tem-
perature drops below 40° F (4.5° C) the switch opens and