Manitowoc Marine Q 1000, Service Technician'S Handbook

Page: 109 / 179

–99–
NOTE: If two columns have matching high numbers, a
procedure was not performed properly and/or
supporting material was not analyzed correctly.
FINAL ANALYSIS
The column with the highest number of check marks
identifies the refrigeration problem.
COLUMN 1 - HARVEST VALVE LEAKING
Replace the valve as required.
COLUMN 2 - LOW CHARGE/TXV STARVING
Normally, a starving expansion valve only affects the
freeze cycle pressures, not the harvest cycle
pressures. A low refrigerant charge normally affects
both pressures. Verify the ice machine is not low on
charge before replacing an expansion valve.
1. Add refrigerant charge in 2 to 4 oz. increments as a
diagnostic procedure to verify a low charge. Do not
add more than 30% of nameplate refrigerant
charge. If the problem is corrected, the ice machine
is low on charge. Find the refrigerant leak.
2. The ice machine must operate with the nameplate
charge. If the leak cannot be found, proper
refrigerant procedures must still be followed
Change the liquid line drier. Then, evacuate and
weigh in the proper charge.
3. If the problem is not corrected by adding charge,
the expansion valve is faulty.
On dual expansion valve ice machines, change
only the TXV that is starving. If both TXV’s are
starving, they are probably good, and are being
affected by some other malfunction, such as low
charge.