Manitowoc b970 series, Technician'S Handbook

Page: 217 / 264

Part Number STH025 8/12 217
9. Follow the normal evacuation procedure, except
replace the evacuation step with the following:
A. Pull vacuum to 1000 microns. Break the
vacuum with dry nitrogen and sweep the
system. Pressurize to a minimum of 5 psig

(35 kPa,.35 bar).
B. Change the vacuum pump oil.
C. Pull vacuum to 500 microns. Break the
vacuum with dry nitrogen and sweep the
system. Pressurize to a minimum of 5 psig
(35 kPa,.35 bar).
D. Change the vacuum pump oil.
E. Pull vacuum to 500 microns. Run the vacuum
pump for 1/2 hour on self-contained models,
1 hour on remotes.
NOTE:
You may perform a standing vacuum test to
make a preliminary leak check. You should use an
electronic leak detector after system charging to be
sure there are no leaks.
10. Charge the system with the proper refrigerant to
the nameplate charge.
11. Operate the ice machine for one hour. Then,
check the pressure drop across the suction line
filter-drier.
A. If the pressure drop is less than 1 psig

(7 kPa,.7 bar), the filter-drier should be
adequate for complete cleanup.
B. If the pressure drop exceeds 1 psig (7 kPa,.7
bar), change the suction line filter-drier and
the liquid line drier. Repeat until the pressure
drop is acceptable.
12. Operate the ice machine for 48-72 hours. Then
remove the suction line drier and change the
liquid line drier.
13. Follow normal evacuation procedures.
Important
Dry nitrogen is recommended for this procedure.
This will prevent CFC release.