Refrigeration System Service: R-404A; January - Scotsman SCE275 Serivce Manual

SCE275

Refrigeration System Service: R-404A

This ice machine uses R-404A refrigerant and
polyolester oil. Do NOT use mineral oil in this
refrigeration system.
R-404A is a "Near Azeotrope" so liquid charging
is required:
¤
Weigh in as liquid as much of the charge as
possible into the discharge line.
¤
Install a sight glass between the manifold
and the suction side hose and carefully
meter liquid into the suction side, using the
manifold valve to "flash off" the liquid before
it enters the ice machine. Do this until the
proper amount of refrigerant has been
weighed into the system.
When the system is serviced, a special liquid
line drier is required. It is included with
replacement compressors.
R-404A is not compatible with mineral oil, so
these ice machines use Polyolester oil.
Polyolester oil absorbs water very easily. When
one of these refrigeration systems is opened for
service, it must be re-sealed as soon as
possible (15 minutes maximum).
Special leak detection equipment is required to
locate small refrigerant leaks. Usually a leak
detector capable of detecting a Halongenated
refrigerant or R-134a will work. Check with the
leak detector manufacturer if in doubt.
Allen
Wrench
Torque Stem to
6-8 ft. lb.
Torque Stem Cap to
8-12 ft. lb.
Torque Core
Cap to 7-12
ft. lb.
Access Valves
Note: There are no valve
cores in this valve.

January 2003

Page 36
Liquid Charging
In preparation for charging, the low side hose should
have a sight glass, and/or a restrictor device (such as
a "Charge Faster") installed in it for metering liquid
into the low side of the system.
1. After a thorough evacuation to at least 300 microns,
shut off the manifold valves and switch off the vacuum
pump.
2. Place a drum of R-404A onto an electronic scale.
3. Attach the charging hose to the drum.
4. Open the valve on the drum and purge the charging
hose.
5. Zero out the scale.
6. Shut the low side access valve at the ice machine.
7. Open the discharge manifold valve full open.
8. Watch the scale, when the correct charge is shown,
shut the manifold valve.
Note: If all of the charge will not "go in" the discharge
side:
A. Shut the discharge access valve at the ice
machine.
B. Switch the machine on.
C. Open the low side access valve at the ice
machine.
D. Open the low side manifold valve and observe
the sight glass to be certain that only gas is flowing
into the system.
E. When the proper charge is indicated on the
scale, shut off the manifold valve(s).
9. Shut off the valve on the refrigerant drum.
10. Re-open the manifold valves until all liquid has
flowed out of the hoses.
11. Shut the low side access valve on the ice
machine.
12. Remove hoses from ice machine and replace all
caps.