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AIRFLOW CHECK - Both airflow and refrigerant charge must be monitored for proper system set-up. It may be necessary
to alternately check and adjust the airflow and the refrigerant charge.
NOTE: Be sure that filters and indoor and outdoor coils are clean before testing.
To determine temperature drop across indoor coil (Delta-T), measure the entering air dry bulb (DB) and wet bulb (WB)
temperatures at the indoor coil. Find Delta-T in Table 4. Measure coil's leaving air DB and subtract that value from entering
air DB. The measure difference should be within ±3ºF (±1.8ºC) of table value; if too low, decrease the indoor fan speed
(refer to indoor unit for information). If the Delta-T is too high, increase the indoor fan speed. Repeat charging procedure
adn Delta-T (air flow adjustment) procedure until both are correct.
Example: Assume entering air DB - 72, WB - 64, leaving DB - 53. Therefore, Delta-T should be 15 (per table); delta across
coil is 72 - 53 or 19 (which is 4ºF higher than table value). Action necessary: increase fan speed.
Dry bulb temperature of air entering indoor coil (ºF)
Table 4. Evaporator Coil Delta-T
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
75 22 22 22 21 21 20 19 19 18 17 16 15 14 13
74 21 21 21 20 19 19 18 17 16 16 15 14 13 12
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
ºF
57 58 59 60 61 62 63 64 65 66 67 68 69 70
[Wet bulb temperature of air entering indoor coil]
Capacity
-018
-024
RFC Size
0.052
0.060
Outdoor Temp (ºF)
C
-018
A
-024
P
-030
A
-036
C
I
-042
T
-048
Y
-060
* Suction line saturation temperature minus suction line temperature. All ,easurements are at the service valves and are based on 80 db / 67 wb
indoor temperature.
31-5000749 Rev. 0
Table 5. RFC Sizes
-030
-036
0.067
0.072
Table 6. Superheat Valvue (RFC)* ±1ºF (0.5ºC)
65
70
75
21
21
21
25
25
24
20
20
19
26
25
24
25
24
22
27
26
24
28
26
24
Figure 14. NS16AC (cont)
-042
-048
-060
0.081
0.083
0.097
80
85
19
18
23
22
17
15
22
20
20
17
22
19
21
18
Page 29
90
85
100
16
13
9
21
19
16
13
9
7
18
15
12
15
12
7
16
12
8
14
10
6
105
1
13
4
10
6
3
4
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