Service Manual

Section 7 Refrigeration System
Part No. 80-1100-3 7-29
HPR DIAGNOSTICS
Steps 1 through 4 can be quickly verified without
attaching a manifold gauge set or thermometer.
All questions must have a yes answer to continue
the diagnostic procedure.
1. Liquid line warm?
(Body temperature is normal)
If liquid line is warmer or cooler than body
temperature, refer to headmaster diagnostics.
2. Ice fill pattern normal?
Refer to “Ice Formation Pattern” if ice fill is not
normal.
3. Freeze time normal?
(Refer to Cycle Times/Refrigerant Pressures/24
Hour Ice Production Charts)
Shorter freeze cycles - Refer to headmaster
diagnostics.
Longer freeze cycles - Refer to water system
checklist, then refer to Refrigeration Diagnostic
Procedures.
4. Harvest time is longer than normal and control board
indicates safety limit #2?
(Refer to Cycle Times/Refrigerant Pressures/24
Hour Ice Production Charts)
Connect refrigeration manifold gauge set to the
access valves on the front of the ice machine, and a
thermometer thermocouple on the discharge line
within 6" of the compressor (insulate thermocouple).
5. Establish baseline by recording suction and
discharge pressure, discharge line temperature and
freeze & harvest cycle times. (Refer to section 7
“Operational Analysis” for data collection detail).
6. Freeze cycle Head Pressure 220 psig or higher?
If the head pressure is lower than 220 psig refer to
headmaster diagnostics.
7. Freeze cycle Suction Pressure normal?
Refer to analyzing suction pressure if suction
pressure is high or low.
8. Discharge line temperature is 160°F (71.1°C) or
higher at end of freeze cycle?
If less than 160°F (71.1°C) check expansion valve
bulb mounting and insulation.
9. Harvest cycle suction and discharge pressures are
lower than indicated in the cycle times/refrigerant
pressures/24 hour ice production chart?
Replace Harvest Pressure Regulating system (HPR
Valve and HPR solenoid valve).