Instruction Manual

Page 2
4 - Subtract the liquid line temperature from the
saturation temperature (according to the chart) to
determine subcooling (Saturation temperature -
Liquid line temperature = Subcooling Value).
5 - Compare the subcooling value with those in table for
the specic system match. If subcooling is greater
than shown, recover some refrigerant. If subcooling
is less than shown, add refrigerant.
6 - Repeat steps 1 – 5 anytime refrigerant is added or
recovered.
7 - For Heat Pump models – Switch to heating mode
and let the system stabilize at least 10 minutes.
Then conrm that the pressures obtained from the
connected gauges match the normal operating
pressures (heating mode) in table for the specic
system match.
Charge Using Normal Operating Pressures/Approach
Method (High Capacity)
Outdoor Temperature ≥ 65ºF (18.3ºC)
For best results, indoor temperature should be 70°F (21°C)
to 80°F (26°C). Monitor system pressures while charging.
1 - Attach pressure gauge set to liquid and suction
service valves.
2 - Operate unit for at least ve (5) minutes to allow
system pressures to stabilize. Record pressures.
3 - Compare stabilized pressures with those provided
in table for the specic system match. Minor
variations are to be expected; signicant di󰀨erences
could mean that the system is not properly charged
or that a problem exists with some component in
the system. The approach method is not valid for
grossly over or under-charged systems.
4 - Pressures higher than those listed indicate that the
system is overcharged. Pressures lower than those
listed indicate that the system is undercharged. Add
or recover charge until the pressures are within the
tolerances on the table.
5 - Repeat steps 2 – 4 each time refrigerant is added
or recovered.
6 - Verify charge using the approach method.
7 - Use the same thermometer to measure and record
liquid line temperature.
8 - Subtract the outdoor temperature from the liquid
line temperature to determine the approach value
(Liquid line temperature – Ambient temperature =
Approach Temperature).
9 - The approach temperature should match value
given in table for the specic system match. If the
values don’t agree with the those in table, add
refrigerant to lower the approach temperature or
recover refrigerant from the system to increase the
approach temperature.
10 - Operate unit for at least ve (5) minutes to allow
system pressures to stabilize.
11 - Repeat steps 7 – 10 each time refrigerant is added
or recovered.
12 - For Heat Pump models – Switch to heating mode
and let the system stabilize at least 10 minutes.
Then conrm that the pressures obtained from the
connected gauges match the normal operating
pressures (heating mode) in table for the specic
system match.
Outdoor Temperature < 65ºF (18.3ºC)
When the outdoor ambient temperature is below 65ºF
(18.3ºC) it may be necessary to restrict the air ow through
the outdoor coil to achieve pressures in the 325-375 psig
(2240-2485 kPa) range. These higher pressures are nec-
essary for checking the charge. Block equal sections of
air intake panels and move obstructions sideways until
the liquid pressure is in the 325-375 psig (2240-2485 kPa)
range. See gure 1. Once pressure is in range, charge us-
ing Normal Operating Pressures/Approach Method (High
Capacity).
FIGURE 1. Blocking Outdoor Coil
Using the Normal Operating Pressures and Tempera-
tures Table
Tables may be used to help perform maintenance checks.
This table is not a procedure for charging the system and
any minor variations in the pressures may be expected
due to di󰀨erences in installations. However, signicant
deviations could mean that the system is not properly
charged or that a problem exists with some component in
the system.