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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
1. Connect gauge set as illustrated in figure 14.
2. Confirm proper airflow across coil using figure 15.
3. Compare unit pressures with charging sticker,
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 charging sticker on unit or at the
end of this manual.
64ºF and
BELOW
65ºF
and
ABOVE
ABOVE or
BELOW
B
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.
Figure 18. Using HFC-410A Approach (TXV) Charge Method
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
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 14.
2. Confirm proper airflow across coil using figure 15.
3. Compare unit pressures with charging sticker,
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 applicable charging sticker
located on unit access panel or copy located at the
end of this manual. See table 3 for to determine
applicable charging information for specific model.
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
.
Figure 19. Using HFC-410A Subcooling (TXV) Charge Method
