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506637−01 11/10
DO NOT CHARGE UNIT
(Results of charging at low
temperatures not reliable)
START: Measure outdoor ambient temperature
USE WEIGH-IN METHOD
Weigh-in or remove refrigerant
based upon line length
APPº (Approach) Values(F:+/−1.0° [C: +/−0.6°])
1. Connect gauge set as illustrated in figure 15.
2. Confirm proper airflow across coil using figure 17.
3. Compare unit pressures with table 4, Normal
Operating Pressures.
4. Set thermostat to call for heat (must have a cooling
load between 70-80ºF (21−26ºC).
5. When heat demand is satisfied, set thermostat to call
for cooling.
6. Allow temperatures and pressures to stabilize.
7. Record outdoor ambient temperature:
AMBº =_________
8. Record liquid line temperature:
LIQº = __________
9. Subtract to determine approach (APPº):
LIQº_____ − AMBº _____ = APPº_____
10. Compare results with table below.
Figure 19. Using HFC−410A Approach (TXV) Charge Method
64ºF and
BELOW
65ºF
and
ABOVE
ABOVE or
BELOW
APPROACH TXV
If value is greater than shown (high
approach), add refrigerant; if less
than shown (liquid temperature too
close to ambient temperature, low
approach), remove refrigerant.
If refrigerant is added or
removed, retest to confirm
that unit is properly
charged.
Models
ºF (ºC)* −024 −036 −048 −060
Any 6 (3.3) 6 (3.3) 8 (4.4) 4 (2.2)
*Temperature of air entering outdoor coil
DO NOT CHARGE UNIT
(Results of charging at low
temperatures not reliable)
START: Measure outdoor ambient temperature
USE WEIGH-IN METHOD
Weigh-in or remove refrigerant
based upon line length
SCº (Subcooling) Values (F:+/−1.0° [C: +/−0.6°])
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 above noted ranges.
1. Connect gauge set as illustrated in figure 15.
2. Confirm proper airflow across coil using figure 17.
3. Compare unit pressures with table 4, Normal
Operating Pressures.
4. Set thermostat to call for heat (must have a cooling
load between 70-80ºF (21−26ºC)
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.
Figure 20. Using HFC−410A Subcooling (TXV) Charge Method
64ºF and
BELOW
65ºF
and
ABOVE
ABOVE or
BELOW
C
CARDBOARD OR
PLASTIC SHEETS
SUBCOOLING TXV
If value is
MORE than
shown, remove
refrigerant.
MORE or
LESS
If value is LESS
than shown, add
refrigerant.
If refrigerant is
added or removed,
verify charge using
the Approach
Method.
Models
ºF (ºC)* −024 −036 −048 −060
Any 5 (2.7) 6 (3.3) 6 (3.3) 9 (5.0)
*Temperature of air entering outdoor coil