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Refrigeration System Section 7
7-8
Part No. 80-1214-3
ANALYZING SUCTION PRESSURE
NOTE: Analyze discharge pressure before analyzing suction pressure. High or low discharge pressure may be
causing high or low suction pressure.
Suction Pressure High Checklist
Suction 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”
Discharge pressure Discharge pressure is too high, and is affecting suction pressure
(See “Freeze Cycle Discharge Pressure High Checklist”
Improper refrigerant charge Overcharged
Wrong type of refrigerant
Non condensables in system
Other Non-Manitowoc components in system
TXV flooding (check bulb mounting)
Defective compressor
Possible Cause Check/Correct
Improper installation See “Installation/Visual Inspection Checklist”
Discharge pressure Discharge pressure is too low, and is affecting suction pressure (See “Freeze Cycle
Discharge Pressure Low Checklist”)
Improper refrigerant charge Undercharged
Wrong type of refrigerant
Other Non-Manitowoc components in system
Restricted/plugged liquid line drier
Restricted/plugged tubing in suction side of refrigeration system
Expansion valve starving
No water or insufficient pressure
Defective compressor
Moisture in refrigeration system
Dirty Evaporator
Defective Fan Cycle Control
RFC2085/RFC2385 Only - Defe
ctive Head Pressure Control
Revised 8/2003