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MFI Series Refrigeration System Service
Page 31
Refrigeration Service:
General: This ice machine uses R404A refrigerant and polyolester oil. Do NOT use mineral oil in this
refrigeration system.
●When the refrigeration system is serviced, a special liquid line drier is required. It is included with
replacement compressor.
●R404A is not compatible with mineral oil so these ice machines use Polyolester oil. Polyolester oil absorbs
water very easily. A system opened for service 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 Halongenated refrigerant or HFC-134a will work. Check with the leak detector manufacturer if in
doubt.
●Evacuate to 300 microns.
●Liquid charge the system.
Access Valves:
To use the access valves:
●Remove the cap from the stem, use a 3/16 inch Allen wrench to check that the valve is
CLOSED. Then remove the core cap.
●Close the valve and replace the caps when done. The valve must be closed and the caps
tightened.
Instructions for Liquid Charging R404A:
In preparation for charging, the low side hose should have a sight glass, and/or a restricting device (such as a
“Charge Faster”) installed in it for metering liquid into the low side of the system.
1. After a through evacuation shut off the manifold valves and switch off the vacuum pump.
R404A
Tank Must
Be in Liquid
Dispensing
Position.
Check Tank!
Low Side High Side
Torque Stem to 6-8 ft.-lb.
Torque caps to 7-12 ft.-lbs
2. Place a drum of R404A 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
valves.
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.
Hose Connection Schematic for Liquid Charging
12. Remove hoses from ice machine and replace all caps.