Kolpak PR - Condensing Unit Troubleshooting

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Condensing Unit Troubleshooting
Problem
Possible Cause
Corrective Action
Compressor will not run.
Main switch open
Close switch
Fuse blown
Check electrical circuits and motor
winding for shorts or grounds.
Investigate for possible overloading.
Replace fuse after fault is corrected.
Thermal overloads tripped
Overloads are automatically reset.
Check unit closely when unit comes
back on line.
Defective contactor or coil
Repair or replace
System shut down by safety devices
Determine type and cause of shutdown
and correct
No cooling required
None. Wait until cooling is required.
Liquid line solenoid will not open.
Repair or replace coil.
Low pressure switch will not close.
Replace switch
Motor electrical trouble
Check motor for open windings or short
circuit.
Problem
Possible Cause
Corrective Action
Loose wiring
Check all wire junctions. Tighten all
terminal screws.
Compressor noisy or vibrating
Flooding of refrigerant into crankcase
Check superheat setting of expansion
valve
Improper pipe support
Relocate or add hangers
Worn compressor
Replace compressor
High discharge pressure
Non-condensable in system
Recover, evacuate and charge
System overcharged with refrigerant
Remove excess charge
Discharge shut-off valve partially closed
Open valve
Fan not running
Check electrical circuit or replace
defective fan motor
Insufficient condenser air supply
Check for cause and correct
Dirty condenser coil
Clean coil
Low discharge pressure
Faulty head pressure control
Check head pressure control operation.
Suction shut-off valve partially closed
Open valve
Insufficient refrigerant in system
Locate and repair leak, recover,
evacuate and recharge
Low suction pressure
Check for proper refrigerant charge
High suction pressure
Excessive load
Reduce load or add additional
equipment
Expansion valve overfeeding
Secure and insulate TXV bulb or if
required adjust superheat.
Low suction pressure
Lack of refrigerant
Locate and repair leak, recover,
evacuate and charge.
Evaporator dirty or iced
Clean
Clogged liquid line or suction line filter-
drier
Replace filter-drier
Expansion valve malfunctioning
Check and reset for proper superheat
Condensing temperature too low
Check head pressure control
Improper TXV
Check for proper sizing