Analyzing Discharge Pressure During Freeze Or Harvest Cycle - Manitowoc S Service Manual

Refrigeration System
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 sump trough
2. Refer to Operating Pressure Chart for ice machine
being checked.
Use the operating conditions determined in step 1 to
find the published normal discharge pressures.
Freeze Cycle _______
Freeze Cycle Discharge Pressure High Checklist
Possible Cause
Improper installation
Restricted condenser air flow (air-cooled models)
Restricted condenser water flow (water-cooled
models)
Improper refrigerant charge
Other
Freeze Cycle Discharge Pressure Low Checklist
Possible Cause
Improper installation
Improper refrigerant charge
Water regulating valve (water-cooled condensers)
Other
NOTE: Do not limit your diagnosis to only the items listed in the checklists.
7-16
______
______
______
Harvest Cycle _______
See "Installation/Visual Inspection Checklist"
High inlet air temperature (Self-Contained -110°F/43.3°C max.;
Remote - 120°F/49°C max.)
Condenser discharge air recirculation
Dirty condenser filter
Dirty condenser
Defective fan cycling control
Defective fan motor
Low water pressure [20 psi (138 kPa) min.]
High inlet water temperature (90°F/32.2°C max.)
Dirty condenser
Dirty/defective water regulating valve
Water regulating valve out of adjustment
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 (remote models)
See "Installation/Visual Inspection Checklist"
Undercharged
Wrong type of refrigerant
Out of adjustment
Defective
Non-Manitowoc components in system
Defective head pressure control valve (remote models)
Defective fan cycle control
3. Perform an actual discharge pressure check.
Freeze Cycle
PSIG (kPa)
Beginning of Cycle __________
Middle of Cycle __________
End of Cycle __________
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.
Check/Correct
Check/Correct
Section 7
Harvest Cycle
PSIG (kPa)
__________
__________
__________
Part Number 80-1480-3