Page 16
505328M 06/09
NOTE
− Use gauge ports on vapor line valve and liquid valve for evacuating refrigerant
lines and indoor coil. Use vapor gauge port to measure vapor pressure during charging.
OUTDOOR
COIL
CHECK
EXPANSION VALVE
BI−FLOW
FILTER /
DRIER
TO
HFC−410
A DRUM
LOW
PRESSURE
COMPRESSOR
REVERSING VALVE
VAPOR LINE
VALVE
MUFFLER
NOTE − ARROWS INDICATE
DIRECTION OF REFRIGERANT FLOW
CHECK EXPANSION VALVE
INDOOR UNIT
OUTDOOR UNIT
LIQUID
SERVICE
PORT
GAUGE MANIFOLD
DISTRIBUTOR
INDOOR
COIL
VAPOR
SERVICE
PORT
HIGH
PRESSURE
LIQUID
LINE
VALVE
Figure 25. XP15 Cooling Cycle (Showing Gauge Manifold Connections)
1. Determine the desired
D
T
Measure entering air temper-
ature using dry bulb (
A
) and wet bulb (
B
).
D
T
is the intersect-
ing value of
A
and
B
in the table (see triangle).
2. Find temperature drop across coil
Measure the coil’s dry
bulb entering and leaving air temperatures (
A
and
C
). Tem-
perature Drop Formula: (
T
Drop
) =
A
minus
C
.
3. Determine if fan needs adjustment
If the difference between
the measured
T
Drop
and the desired
D
T
(T
Drop
–
D
T)
is within
+3º, no adjustment is needed. See examples: Assume
D
T
=
15 and
A
temp. = 72º, these
C
temperatures would necessi-
tate stated actions:
Cº
T
Drop
–
D
T
=
ºF
ACTION
53º
19
–
15
=
4
Increase the airflow
58º
14
–
15
=
−1
(3º range) no change
62º
10
–
15
=
−5
Decrease the airflow
4. Adjust the fan speed
See indoor unit instructions to in-
crease/decrease fan speed.
Changing air flow affects all temperatures; recheck tempera-
tures to confirm that the temperature drop and
D
T are within
+3º.
D
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
76
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
57 58 59 60 61 62 63 64 65 66 67 68 69 70
Temp.
of air
entering
indoor
coil ºF
INDOOR
COIL
DRY
BULB
DRY
BULB
WET
BULB
B
T
Drop
19º
A
Dry−bulb
Wet−bulb ºF
A
72º
B
64º
C
53º
air flow
air flow
All temperatures are
expressed in ºF
Figure 26. Checking Indoor Airflow over Evaporator Coil using Delta−T Chart
WEIGH IN
1. Check Liquid and suction line pressures
2. Compare unit pressures with table 5,
Normal Operating Pressures
.
3. Conduct leak check; evacuate as
previously outlined.
4. Weigh in the unit nameplate charge plus
any charge required for line set differences
over feet.
Liquid Line
Set Diameter
Ounces per 5 feet (g per 1.5 m)
adjust from 15 feet (4.6 m) line set*
3/8" (9.5 mm)
3 ounce per 5’ (85 g per 1.5 m)
NOTE − *If line length is greater than 15 ft. (4.6 m), add this
amount. If line length is less than 15 ft. (4.6 m), subtract this
amount.
Refrigerant Charge per Line Set Length
This nameplate is for illustration purposes
only. Go to actual nameplate on outdoor
unit for charge information.
Figure 27. Using Weigh In Method
