Analyzing Discharge Pressure During Freeze Or Harvest Cycle - Manitowoc FLAKE/CHIPLET QC0700 Service Manual

Section 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.
Discharge Pressure High Checklist
Possible Cause
Improper installation
Restricted condenser air flow
Improper refrigerant charge
Other
Discharge Pressure Low Checklist
Possible Cause
Improper installation
Improper refrigerant charge
Other
NOTE: Do not limit your diagnosis to only the items listed in the checklists.
Part No. 80-1214-3
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.
See "Installation/Visual Inspection Checklist"
High inlet air temperature
Condenser discharge air recirculation
Dirty condenser fins
Defective fan motor
Defective fan cycle control (QC700/QF800 only)
Overcharged
Non-condensables in system
Wrong type of refrigerant
Non-Manitowoc components in system
High side refrigerant lines/component restricted (before mid-condenser)
Defective head pressure control valve (RFC2085/RFC2385 only)
See "Installation/Visual Inspection Checklist"
Undercharged
Wrong type of refrigerant
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
Refrigeration System
Check/Correct
Check/Correct
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