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5. Subtract the outdoor ambient temperature from the
liquid line temperature to determine the approach
temperature.
_____ °
Liquid Line Temperature °F
_____ °
Outdoor Ambient Temperature °F
_____ °
Approach Temperature °F
–
=
6. Compare the approach value with those shown in
Table 8. If the values to do not agree with those
provided in Table 8, add refrigerant to lower the
approach temperature or recover refrigerant from the
system to increase the approach temperature.
Approach Values for TXV Systems
Approach value is the liquid line temperature
minus the outdoor ambient temperature (±1°F).
NOTE: For best results, use the same digital
thermometer to check both outdoor ambient and
liquid temperatures.
Table 8
l
e
d
o
M
4
2
-
6
3
-
8
4
-
0
6
-
F
°
.
p
m
e
T
8
9
8
8
Check Charge Using Normal Operating Pressures
Use Table 7 on page 15 to perform maintenance checks.
Table 7 is not a procedure for charging the system. Minor
variations in these pressures may be due to differences in
installations. Significant deviations could mean that the
system is not properly charged or that a problem exists
with some component in the system.
