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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 set 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.
If value is MORE
than shown, remove
refrigerant.
1. Confirm proper airflow across coil using Figure
18.
2. Compare unit pressures with Table 5 or 6.
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 7):
SATº = ______
10. Subtract to determine subcooling (SCº):
SATº_____ − LIQº _____ = SCº _____
11. Compare results with Tables 3 or 4 .
Figure 21. HFC−410A Subcooling Charge
MORE or
LESS
If value is LESS
than shown, add
refrigerant.
ABOVE or
BELOW
65ºF
(18.3ºC)
and
ABOVE
64ºF
(17.7ºC) and
BELOW
Table 3.
Subcooling (SC) Values TXV System − ºF
(ºC) +1ºF (0.5ºC) (1−PHASE)
TSA*S4 50Hz International (1−Phase)
F(5C) −024 −030 −036 −048 −060
65 (18) 10 6 5 2 4
70 (21) 10 6 5 2 4
75 (24) 11 6 6 3 4
80 (27) 11 7 6 3 5
85 (29) 11 7 6 3 5
90 (32) 11 7 7 4 5
95 (35) 11 7 7 4 5
100 (38) 11 7 7 5 5
105 (41) 11 7 7 5 5
110 (43) 11 8 7 5 5
115 (45) 11 8 8 6 5
Table 4.
Subcooling (SC) Values TXV System − ºF
(ºC) +1ºF (0.5ºC) (3−PHASE)
TSA*S4 50Hz International (3−Phase)
F(5C) −036 −048 −060
65 (18) 8 2 2
70 (21) 8 2 3
75 (24) 9 3 3
80 (27) 9 3 3
85 (29) 9 4 4
90 (32) 10 4 4
95 (35) 10 4 4
100 (38) 10 5 4
105 (41) 10 5 4
110 (43) 10 5 4
115 (45) 10 6 4
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