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Section 7 Refrigeration System
Part No. 80-1214-3 7-7
ANALYZING DISCHARGE PRESSURE
DURING FREEZE OR HARVEST CYCLE
Procedure
1. Determine the ice machine operating conditions:
Air temp. entering condenser ______
Air temp. around ice machine ______
Water temp. entering water reservoir ______
2. Refer to Cycle Times/24 Hour Ice Production/
Refrigeration Pressure Chart for ice machine being
checked.
Use the operating conditions determined in step 1 to
find the published normal discharge pressures.
Compare to actual discharge pressure readings.
3. Measure the actual discharge pressure.
4. Compare the actual discharge pressure (step 3) with
the published discharge pressure (step 2).
The discharge pressure is normal when the actual
pressure falls within the published pressure range for the
ice machine’s operating conditions.
Discharge Pressure High Checklist
Discharge Pressure Low Checklist
NOTE: Do not limit your diagnosis to only the items listed in the checklists.
Possible Cause Check/Correct
Improper installation See “Installation/Visual Inspection Checklist”
Restricted condenser air flow High inlet air temperature
Condenser discharge air recirculation
Dirty condenser fins
Defective fan motor
Defective fan cycle control (QC700/QF800 only)
Improper refrigerant charge Overcharged
Non-condensables in system
Wrong type of refrigerant
Other Non-Manitowoc components in system
High side refrigerant lines/component restricted (before mid-condenser)
Defective head pressure control valve (RFC2085/RFC2385 only)
Possible Cause Check/Correct
Improper installation See “Installation/Visual Inspection Checklist”
Improper refrigerant charge Undercharged
Wrong type of refrigerant
Other Non-Manitowoc components in system
Defective head pressure control valve (RFC2085/RFC2385 only)
Defective fan cycle control (QC700/QF800 only)
Suction pressure is too low and affecting discharge pressure. Refer to
suction pressure low checklist.
No water or insufficient pressure
Starving expansion valve
Defective compressor
Moisture in refrigeration system
Revised 8/2003