Manitowoc STH042 4/16, Technician'S Handbook

Page: 122 / 146

122 Part Number STH042 4/16
SEVERE SYSTEM CONTAMNATON CLEANUP
PROCEDURE
1. Remove the refrigerant charge.
2. Remove the compressor.
3. Disassemble the harvest solenoid valve. If burnout
deposits are found inside the valve, install a rebuild
kit, and replace the TXV and head pressure control
valve.
4. Wipe away any burnout deposits from suction and
discharge lines at compressor.
5. Sweep through the open system with dry nitrogen.
6. Install a new compressor and new start components.
7. Install suction line filter-drier in front of compressor.
8. Install a new liquid line drier.
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.
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.
D. Change the vacuum pump oil.
E. Pull vacuum to 500 microns. Run the vacuum
pump for 1 additional hour.
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 2 psig, the filter-
drier should be adequate for complete cleanup.
B. If the pressure drop exceeds 2 psig, 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. Replace
the suction line and liquid line drier if necessary.
13. Follow normal evacuation procedures.