CyberAiR DX Floor Mounted IOM Manual
3. Referring to Section 3.0, start the A/C system
and use the system controller to lower the
room temperature set point 3-5°F below actual
room temperature thus ensuring cooling
remains on as the unit is charged.
When fine tuning the charge on cool days it may be
necessary to restrict the airflow across the
condenser coil to raise the pressure. The fan closest
to the header must be running. When fine tuning the
charge, ensure the pressures are correct for the type
of refrigerant used. Refer to the tables in Section
2.9.6 for the operating temperature and pressure
ranges for R-410A refrigerant.
4. Block off a portion of the intake air to the
condenser until a constant discharge pressure
can be obtained. This will lower the possibility
of
overcharging. Allow the discharge pressure to
rise to 445-480 psig and hold it constant.
5. Slowly meter
liquid
refrigerant through the suction
side while watching the pressure gauges and
monitoring superheat and sub-cooling
temperatures.
CAUTION
Add liquid refrigerant slowly to prevent the
refrigerant oil from “washing out” of the
compressor.
6. Take a superheat temperature reading near the
feeler bulb from the auxiliary control module with
the temperature measuring device being well
insulated. The ideal superheat temperature is 12-
15°F. Maximum allowable superheat temperature
is 20°F.
CAUTION
Do not exceed 20°F superheat. Exceeding
this temperature may cause failure of the
compressor.
7. While monitoring the pressure, take a sub-
cooling temperature reading on the output side
of the condenser. The sub-cooling temperature
should be 10-20°F.
8. If necessary, (slowly) add
liquid
refrigerant to
the suction side to achieve the correct sub-
cooling temperature.
CAUTION
Remove the blockage from the air intake of
the condenser.
9. Fill out the applicable sections of the
Warranty Registration and Start-Up
Checklist.
2.9.5.1
-20ºF Variable Speed Control
The following instructions are for charging systems
with condenser variable fan speed control using
R-410A refrigerant.
1. Partially block the airflow to the condenser
with cardboard to raise the discharge
pressure. Allow the discharge pressure to rise
high enough to start the first fan only, then
maintain a constant
pressure between 445-470 psig. This will lower
the possibility of overcharging.
2. Slowly meter
liquid
refrigerant through the suction
side while watching the pressure gauges and
monitoring superheat and sub-cooling
temperatures.
CAUTION
Add liquid refrigerant slowly to prevent the
refrigerant oil from “washing out” of the
compressor.
3. Take a superheat temperature reading near the
feeler bulb from the thermal expansion valve with
the temperature measuring device being well
insulated. The ideal superheat temperature is 12-
15°F. Maximum allowable superheat temperature
is 20°F.
4. While monitoring the pressure, take a sub-
cooling temperature reading on the output side
of the condenser. The sub-cooling temperature
should be 10-20°F.
5. If necessary, (slowly) add
liquid
refrigerant to the
suction side to achieve the sub-cooling
temperature.
6. If the unit has hot gas reheat (optional), the
previous steps are still followed except the hot
gas reheat valve must be open to allow
refrigerant
to flow into the reheat coil to obtain the proper
amount of refrigerant charge. This can be done
by using the system controller to enable a call
for dehumidification (lower the humidity set
point). This process may need to be repeated
several times. After cycling the system through
the hot gas reheat cycle, recheck the system
charge with the system only in the Cooling
mode.
CAUTION
Remove the blockage from the air intake of
the condenser.
7. Fill out the applicable sections of
Warranty Registration and Start-Up
Checklist.
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