Section 7 Refrigeration System
7-27
H.P.R. SYSTEM FAILURE CHART
Symptoms Possible Causes
Freeze
Cycle
The ice machine functions properly. (The H.P.R. solenoid is
closed, preventing refrigerant flow into the H.P.R. valve.)
Harvest
Cycle
The discharge pressure is low or normal and the suction
pressure is low, which causes extended harvest times.
The ice machine usually continues to run, although with
extended harvest times, ice production decreases.
If the harvest time exceeds 3.5 minutes for three
consecutive cycles, the control boards stops ice machine
operation on Safety Limit #2.
Low discharge pressure during the freeze cycle causes
the H.P.R. valve to appear as though it is not feeding
properly during the harvest cycle.
Verify/correct discharge pressure during the freeze cycle
PRIOR TO assuming the H.P.R. valve is faulty.
H.P.R. solenoid remains closed
-or-
H.P.R. valve remains closed
Freeze
Cycle
The discharge pressure is normal and the suction pressure
is slightly high or normal.
Harvest
Cycle
The discharge pressure is slightly low or normal and the
suction pressure is slightly low or normal.
NOTE: The liquid line solenoid closes when the ice
machine shuts off. The discharge pressure should remain
higher than the suction pressure. If the discharge and
suction pressures equalize immediately, a solenoid valve
(H.P.R., liquid line or hot gas valve) is most likely leaking.
Solenoid leaks or remains open
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