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Units Delivered Void of Charge
If the system is void of refrigerant, clean the system using
the procedure described below.
1.Use nitrogen to pressurize the system and check for
leaks. Repair leaks, if possible.
2.Evacuate the system to remove as much of the moisture
as possible.
3.Use nitrogen to break the vacuum and install the provided
filter drier in the system.
4.Evacuate the system again. Then, weigh the appropriate
amount of R−410A refrigerant (listed on unit nameplate)
into the system.
5.Monitor the system to determine the amount of moisture
remaining in the oil. Use test kit 10N46 to verify that the
moisture content is within the kit’s dry color range. It
may be necessary to replace the filter drier several
times to achieve the required dryness level. If system
dryness is not verified, the compressor will fail in
the future.
Pre−charge Airflow Check of Temperature Drop
across Evaporator Coil (Delta−T)
NOTE − Be sure that filters and indoor and outdoor coils are
clean before testing
Measure the entering air dry bulb (DB) and wet bulb (WB)
temperatures at the indoor coil. Find Delta−T in table 3. Mea-
sure evaporator coil’s leaving air DB and subtract that value
from the entering air DB. The measured difference should
be within +
3ºF (+1.8ºC) of table value. If Delta−T is too low,
decrease the indoor fan speed (refer to indoor unit for infor-
mation). If the Delta−T is high, increase the indoor fan speed.
Repeat charging procedure and Delta−T (air flow adjust-
ment) procedure until both are correct.
Example:
Assume entering air DB − 72, WB − 64, leaving DB − 53.
Delta−T should be 15 (per table); delta across coil is 19 (72
minus 53) which is 4ºF higher than table value; therefore, in-
crease fan speed.
TABLE 3
80 24 24 24 23 23 22 22 22 20 19 18 17 16 15
78 23 23 23 22 22 21 21 20 19 18 17 16 15 14
temperature
76 22 22 22 21 21 20 19 19 18 17 16 15 14 13
of air entering
74 21 21 21 20 19 19 18 17 16 16 15 14 13 12
indoor coil
72 20 20 19 18 17 17 16 15 15 14 13 12 11 10
70 19 19 18 18 17 17 16 15 15 14 13 12 11 10
57 58 59 60 61 62 63 64 65 66 67 68 69 70
Wet bulb temperature of air entering indoor coil
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