INITIAL SYSTEM CHARGE
CyberAiR DX Floor Mounted IOM Manual
NOTE
When pulling a vacuum, the Schrader valves will
unnecessarily restrict the openings, increasing the
evacuation time. During the evacuation process it is
recommended to remove the Schrader valve cores
with a Schrader valve removal tool and draw the
vacuum through the port on the removal tool.
4. If you cannot evacuate the system below 1500
microns, close the vacuum pump isolation valve and
perform a rate-of-rise test by observing the standing
pressure over time. If the pressure rises slowly (up to
200 microns in 15 minutes) it indicates moisture is in the
system that still needs to be boiled off. Proceed to step
#5. If the pressure rises rapidly up to atmospheric
pressure (more than 50 microns per minute) it indicates
a leak that wasn’t detected during step #2. In this case
troubleshoot the entire system for leaks and repair
them. Then begin the initial evacuation process again
starting at step #3.
5. If no leaks are detected after the initial vacuum,
release the vacuum and pressurize the system with 2-3
lbs of dry nitrogen. Allow the system to stand for two
hours with the dry nitrogen charge. This gives time for
the nitrogen molecules to disperse in the system
absorbing moisture.
6. After two hours, release the pressure. Then turn on
the vacuum pump and evacuate the system a second
time down to 1500 microns or less. Close the vacuum
pump isolation valve and pressurize the system again
with dry nitrogen and allow the system to stand for
two hours as in step #5.
7. After two hours release the pressure. Turn on the
vacuum pump and complete the process of
evacuating the system, this time with a goal of
achieving a 250 micron vacuum or less. Close the
vacuum pump isolation valve. When you can hold the
vacuum at 500 microns or lower for at least 2 hours
with no significant rise in pressure, the system is ready
to charge.
8. Replace the Schrader valve cores if you removed
them during the evacuation steps. You may now
introduce the refrigerant charge through the
Schrader valves.
2.9.5 Refrigerant Charging Procedures
R-410A refrigerant must be weighed in when
performing the charge. Referring to Section 2.9.3,
calculate the estimated amount of refrigerant
needed for your system.
When charging a system using a blended
refrigerant, it is essential that the composition of
the refrigerant is maintained. To ensure correct
composition, introduce the refrigerant (R-410A)
into the system in liquid form rather than vapor
form. Cylinders which are not provided with dip
tubes should be inverted to allow
only liquid
refrigerant to charge the system. Keeping the
temperature of the cylinder below 85°F will help
maintain the correct refrigerant composition while
the cylinder is emptied.
WARNING
If refrigerant gas is released in an enclosed area, it
may accumulate in low areas and near the floor
displacing available oxygen. If a major leak occurs,
there is a risk of asphyxiation. In such case the area
should be immediately evacuated and ventilated.
Personnel should remain away from the area until it
is determined to be safe.
Follow the step by step instructions below to charge
systems using R-410A refrigerant. The initial
charge will be performed by introducing liquid
refrigerant to the discharge side of the compressor
or an available liquid line port with the A/C unit
turned Off.
1. Bleed air from hoses and break the vacuum by
supplying
liquid
refrigerant (R-410A) to the
discharge port near the compressor until the
pressure is equalized. This holding charge
allows the low pressure switch to “hold”
enabling the compressor to operate
throughout the process of charging the system.
Once the initial charge is completed, refrigerant
will need to be added with the unit running.
CAUTION
An adequate heat load must be supplied to
ensure a proper charge.
2. Disconnect the refrigerant cylinder from the
discharge side of the compressor and connect it
to the suction side.
2-20
FINE TUNING THE SYSTEM CHARGE
