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Charge Verification − Approach Method − AHRI Testing
1− Using the same thermometer, compare liquid tempera-
ture to outdoor ambient temperature.
Approach Temperature = Liquid temperature (at con-
denser outlet) minus ambient temperature.
2− Approach temperature should match values in table
11. An approach temperature greater than value
shown indicates an undercharge. An approach tem-
perature less than value shown indicates an over-
charge.
3− The approach method is not valid for grossly over or
undercharged systems. Use tables 5 through 10 as a
guide for typical operating pressures.
TABLE 11
APPROACH TEMPERATURES
L Series
Unit
Liquid Temp. Minus Ambient Temp.
1st Stage 2nd Stage 3rd Stage 4th Stage
120 CAV
8°F + 1
(4.4°C + 0.5)
6°F + 1
(3.3°C + 0.5)
NA NA
120
MSAVt
6°F + 1
(3.3°C + 0.5)
6°F + 1
(3.3°C + 0.5)
NA NA
240 CAV
6°F + 1
(3.3°C + 0.5)
6°F + 1
(3.3°C + 0.5)
6°F + 1
(3.3°C + 0.5)
6°F + 1
(3.3°C + 0.5)
240
MSAV
6°F + 1
(3.3°C + 0.5)
6°F + 1
(3.3°C + 0.5)
6°F + 1
(3.3°C + 0.5)
6°F + 1
(3.3°C + 0.5)
288 CAV
6°F + 1
(3.3°C + 0.5)
6°F + 1
(3.3°C + 0.5)
6°F + 1
(3.3°C + 0.5)
6°F + 1
(3.3°C + 0.5)
288
MSAV
6°F + 1
(3.3°C + 0.5)
6°F + 1
(3.3°C + 0.5)
6°F + 1
(3.3°C + 0.5)
6°F + 1
(3.3°C + 0.5)
IV− SYSTEMS SERVICE CHECKS
A−Cooling System Service Checks
SCA/SCB units are factory charged and require no further ad-
justment; however, charge should be checked periodically us-
ing the approach method. The approach method compares
actual liquid temperature with the outdoor ambient tempera-
ture. See section III−CHARGING.
V−MAINTENANCE
WARNING
Electric shock hazard. Can cause injury
or death. Before attempting to perform
any service or maintenance, turn the
electrical power to unit OFF at discon-
nect switch(es). Unit may have multiple
power supplies.
A−Filters
Units are equipped with filters as shown in table 12. Units
will accept 4" filters. Filters should be checked monthly and
replaced when necessary with filters of like kind and size.
Take note of air flow direction marking on filter frame when
reinstalling filters.
TABLE 12
SG/SC Unit
Qty Filter Size − inches (mm)
120 6 16 X 25 X 2 (406 X 635 X 51)
240/288 12 20 X 20 X 2 (508 X 508 X 51)
NOTE−Filters must be U.L.C. certified or equivalent for
use in Canada.
B−Lubrication
All motors and blower wheels used in SCA/SCB units
are prelubricated; no further lubrication is required.
C−Supply Air Blower Wheel
Annually inspect supply air blower wheel for accumulated
dirt or dust. Turn off power before attempting to remove
access panel or to clean blower wheel.
D−Evaporator Coil
Inspect and clean coil at beginning of each season. Clean
using mild detergent or commercial coil cleanser. Check
condensate drain pan and line, if necessary. Flush coil and
condensate drain with water taking care not to get insula-
tion, filters and return air ducts wet. Check connecting
lines and coil for evidence of oil and refrigerant leaks.
E−Condenser Coil
Clean condenser coil annually with detergent or com-
mercial coil cleaner and inspect monthly during the cool-
ing season. Check connecting lines and coil for evidence
of oil and refrigerant leaks.
NOTE−If owner complains of insufficient cooling, the
units’ charge should be checked. Refer to Charging
sections in this manual.
F−Electrical
1− Check all wiring for loose connections.
2− Check for correct voltage at unit (unit operating).
3− Check amp−draw on both condenser fan motor and
blower motor.
Fan Motor Rating Plate ____ Actual ________
Indoor Blower Motor Rating Plate____ Actual____
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