CyberOne EC DX IOM Manual
is not done the refrigerant charge will combine
with moisture in the pipes to form an acid that
will eventually lead to compressor failure. A
triple evacuation procedure with dry nitrogen is
recommended especially for systems with newly
installed refrigerant piping.
NOTES
A vacuum pump should be used that is capable of
evacuating the entire volume of the A/C system,
including newly installed or existing piping. It is
essential to use a well maintained pump that is in
good operating condition. Always ensure it contains
clean, fresh oil. Manufacturers recommend you
change the oil in the pump every 20 minutes to
maintain its ability to remove moisture.
Use high quality hoses ensuring they are free of
defects and don’t leak. It is recommended to use
copper tubing instead of hoses if possible due to the
low vacuum that must be attained when evacuating
the system. The use of short, large diameter hoses
helps reduce evacuation time.
3.
After ensuring there are no leaks, relieve pressure and
evacuate the entire system while maintaining all the
solenoids (and hot gas reheat valve) open. Pull an initial
vacuum of 1500 microns or lower using the suction
and discharge service ports and the service port of the
receiver (if applicable).
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.
2.8.7
Refrigerant Charging Procedures
1.
R407Crefrigerant must be weighed in when
performing the charge. Referring to Section 2.8.5,
calculate the estimated amount of refrigerant needed
for your system.
2.
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 (R407C) 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 R407C refrigerant. The initial charge will be
performed by introducing liquid refrigerant (R407C) to the
discharge side of the compressor or an available liquid line
port with the A/C unit turned Off.
24
INITIAL SYSTEM CHARGE
EVACUATE THE SYSTEM
