Severe System Contamination Cleanup Procedure - Manitowoc QM20 Technician's Handbook

SEVERE SYSTEM CONTAMINATION CLEANUP
PROCEDURE
1. Remove the refrigerant charge.
2. Remove the compressor.
3. Disassemble the hot gas 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.
Refrigerant swee ps are not re commended, as
they release CFCs into the atmosphere. 
Dry nitroge n is re commended fo r th is proce dure.
This will prevent CFC release.
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.
Part Number 80-01111-9 7/10
Important
193