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D − Reversing Valve L1 and Solenoid
A refrigerant reversing valve with electro−mechanical so-
lenoid is used to reverse refrigerant flow during unit op-
eration. The reversing valve requires no maintenance. It
is not repairable. If the reversing valve has failed, it must
be replaced.
E − Crankcase Heater (HR1) and Thermostat
(S40)
The compressor in the unit is equipped with a 70 watt, belly
band type crankcase heater. HR1 prevents liquid from accu-
mulating in the compressor. HR1 is controlled by a thermo-
stat located on the liquid line. When liquid line temperature
drops below 50° F the thermostat closes energizing HR1.
The thermostat will open, de−energizing HR1 once liquid line
temperature reaches 70° F .
F − Drier
A filter drier designed for all SPB*H4 model units is factory
installed in the liquid line. The filter drier is designed to re-
move moisture and foreign matter, which can lead to com-
pressor failure.
Moisture and / or Acid Check
Because POE oils absorb moisture, the dryness of the
system must be verified any time the refrigerant sys-
tem is exposed to open air.
A
c
ompressor oil sample must
be taken to determine if excessive moisture has been
introduced to the oil. Table 4 lists kits available from Lennox
to check POE oils.
If oil sample taken from a system that has been exposed to
open air does not test in the dry color range, the filter drier
MUST be replace.
IMPORTANT
Replacement filter drier MUST be approved for
HFC−410A refrigerant and POE application.
Foreign Matter Check
It is recommended that a liquid line filter drier be replaced
when the pressure drop across the filter drier is greater than
4 psig. To safeguard against moisture entering the system
follow the steps in section IV − sub section B − "Evacuating
the System" when replacing the drier.
G − High/Low Pressure Switch
IMPORTANT
Pressure switch settings for HFC−410A refrigerant
will be significantly higher than units with
HCFC−22.
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 + 15 psi.
An auto-reset, single-pole/single-throw low pressure
switch is located in the suction line. This switch shuts off the
compressor when suction pressure drops below the factory
setting. The switch is closed during normal operating pres-
sure conditions and is permanently adjusted to trip (open)
at 25 + 5 psi. The switch automatically resets when suction
line pressure rises above 40 + 5 psi. Under certain condi-
tions the low pressure switch is ignored. See
Pressure
Switch Circuit
in the Defrost Control description.
TABLE 4
KIT
CONTENTS
TUBE SHELF LIFE
10N46 − Refriger-
ant Analysis
Checkmate−RT700
10N45 − Acid Test
Tubes
Checkmate−RT750A
(three pack)
2 − 3 years @ room
temperature. 3+
years refrigerated
10N44 − Moisture
Test Tubes
Checkmate − RT751
Tubes (three pack)
6 − 12 months @
room temperature. 2
years refrigerated
74N40 − Easy Oil
Test Tubes
Checkmate − RT752C
Tubes (three pack)
2 − 3 years @ room
temperature. 3+
years refrigerated
74N39 − Acid Test
Kit
Sporlan One Shot − TA−1
III − REFRIGERANT SYSTEM
Refer to figure 18 and 19 for refrigerant flow in the heating and cooling modes. The reversing valve is energized during
cooling demand and during defrost.
