Lennox Merit 14ACX−018−230 Installation Instructions Manual page 25

USE WEIGH-IN METHOD
Weigh-in or remove refrigerant
based upon line length
BLOCK OUTDOOR COIL: [sometimes necessary with lower
temperatures] Use cardboard or plastic sheet to restrict the
airflow through the outdoor coil to achieve pressures from
325−375 psig (2240−2585 kPa). Higher pressures are needed
to check charge. Block equal sections of air intake panels and
move coverings sideways until the liquid pressure is in the
CARDBOARD OR
above noted ranges.
PLASTIC SHEET
If refrigerant is added or
removed, verify charge using
the Approach Method.
If value is LESS
than shown, add
refrigerant.
ºF (ºC)* −018 −024
65 (18)
10 (5.6) 10 (5.6)
75 (24)
6 (3.3) 7 (3.9)
85 (29)
6 (3.3) 8 (4.4)
95 (35)
6 (3.3) 9 (5.0)
105 (41)
10 (5.6) 9 (5.0)
115 (45)
10 (5.6) 10 (5.6)
*Temperature of air entering outdoor coil.
ABOVE or
64ºF (17.7ºC)
BELOW
and below
If value is MORE than shown,
remove refrigerant.
MORE or
LESS
SCº (Subcooling) Values (F:+/−1.0° [C: +/−0.6°])
−030 −036
11 (6.1) 13 (7.2)
8 (4.4) 9 (5.0)
6 (3.3) 7 (3.9)
6 (3.3) 8 (4.4)
7 (3.9) 9 (5.0)
8 (4.4) 10 (5.6)
Figure 23. HFC−410A Subcooling TXV Charge
65ºF (18.3ºC) 1. Confirm proper airflow across coil using figure 19.
and above
2. Compare unit pressures with table 4, Normal
Operating Pressures.
3. Set thermostat to call for heat (must have a cooling load
between 70-80ºF (21−26ºC)
4. Connect gauge set
5. Measure outdoor ambient temperature
6. When heat demand is satisfied, set thermostat to call for
cooling
7. Allow temperatures and pressures to stabilize.
NOTE − If necessary, block outdoor coil to maintain 325
− 375 psig.
8. Record liquid line temperature:
LIQº = ______
9. Measure liquid line pressure and use the value to
determine saturation temperature (see table 3):
SATº = ______
10. Subtract to determine subcooling (SCº):
SATº_____ − LIQº _____ = SCº _____
11. Compare results with table below.
−041 −042
9 (5.0) 10 (5.6)
7 (3.9) 7 (3.9)
7 (3.9) 8 (4.4)
7 (3.9) 8 (4.4)
7 (3.9) 8 (4.4)
6 (3.3) 7 (3.9)
Page 25
−047 −048 −059/−060
6 (3.3) 8 (4.4) 8 (4.4)
6 (3.3) 8 (4.4) 7 (3.9)
6 (3.3) 8 (4.4) 8 (4.4)
6 (3.3) 8 (4.4) 7 (3.9)
6 (3.3) 8 (4.4) 6 (3.3)
5 (2.8) 7 (3.9) 6 (3.3)
14ACX SERIES