Scotsman CME306 - Manual (Page 39)

Refrigeration
To use the access valves:
1. Be sure that the valve is closed. Remove the
stem cap and insert a 3/16" allen wrench. Check
that the valve is closed.
2. Remove the port cap and attach refrigerant
manifold hoses.
3. Open the valve and purge the hoses.
4. When service is complete, shut the discharge
access valve first. Then, with the machine running
and the middle hose outlet securely fastened to
the manifold or refrigerant tank (closed) open both
manifold valves. This allows any liquid refrigerant
in the discharge hose to flow thru the manifold and
into the suction side.
5. After the gages have equaled, shut the manifold
valves and the suction access valve.
6. Remove the gages and replace the stem and
port caps. Make certain that they are tightly closed.
Refrigeration System Components
Due to the expected level of training and
experience of a refrigeration mechanic, detailed
instructions regarding the replacement of
refrigeration components will not be presented.
However, critical items will be noted here.
Refrigerant:
1. This ice machine uses R-404A or HP62 as a
refrigerant. It has several unique characteristics.
A. It must use polyol ester refrigerant oil, and that
oil is very water absorbent. The system must not
be open for more than 15 minutes.
B. An electronic leak detector capable of locating
HFC-134a type refrigerant must be used to locate
refrigerant leaks.
C. An HFC type liquid line dryer must be used.
D. A nitrogen purge is required when brazing.
E. When evacuating, use of an electronic micron
gage is recommend. Evacuate to 300 microns.
F. It must be liquid charged:
1. Place a drum or cylinder of R-404A on the
scale, liquid out side up (check container).
2. Attach the charging hose to the cylinder of
R-404A. Open the cylinder’s valve and purge the
hose to the manifold.
3. Close the low side service access valve.
4. Open the discharge side manifold valve and
weigh in the name plate charge. After the charge is
weighed in, wait a moment & re-check the scale.
5. If all of the refrigerant charge has not been
weighed into the discharge side, it must be
carefully added thru the low side. Close the
discharge service access valve.
6. With a sight glass or charge faster in the hose to
the low side port, start the ice machine.
7. Open the low side service access valve.
8. Crack open the low side manifold valve and
watch the scale and sight glass. Open and close
the low side manifold valve to flow liquid into the
manifold but flash off to vapor before it enters the
refrigeration system.
9. After the scale = the correct charge, shut off the
valve on the refrigerant cylinder.
10. With the ice machine running and the
discharge access valve closed, open both manifold
valves to allow the refrigerant in the hoses to enter
the system.
11. Shut the suction service access valve.
12. Remove the refrigeration manifold gages.
13. Replace and tighten all caps.
CME306 & CME456
January 2000
Page 39