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TROUBLESHOOTING
COMPLAINT
1
System short of
capacity
2
Head pressure
too high
3
Head pressure
too low
4
Suction pressure
too high
5
Suction pressure
too low
6
Noisy
compressor
SYMPTOMS
Lower than expected suction
and discharge pressures
Higher than expected
head pressure
Lower than normal suction
pressure
Tripping high pressure switch, or
compressor trips on internal
overload
Sight glass with bubbles
Glycol temperature will not
reach set point
Incorrect superheat
Sight glass with bubbles
Warm suction line, signs of
frost on the TEV and low
system capacity
Compressor cycling due to
low pressure cutout
Oil level below midpoint of the
compressor sight glass during
operation
Noticeable knock in
compressor
Frosted suction line and
compressor shell
CAUSE
Low refrigerant charge
Dirty condenser
Incorrect superheat -
too high
Dirty condenser
Condenser air short
circuiting or location
too hot
Defective condenser fan
motor or blade
Air or non-condensable
gases in the system
Refrigerant over charge
Refrigerant leak or system
undercharged
Plugged filter drier
Insufficient subcooling
Excessive load on the
system
TEV stuck open due to
ice or defect
Incorrect superheat setting
of the expansion valve
See item 3
Plugged TEV or strainer
See item 12
Lack of oil
Worn or scored bearings
Liquid flood back
SOLUTION
Check for leaks, repair, and
recharge. See item 5
Clean. See item 2
Adjust superheat
Clean condenser
Remove obstructions,
causes for air short circuiting
Replace
Purge the system
Remove excess refrigerant
Check for leaks, repair
and recharge
Replace filter drier
Check condenser subcooling
circuit
Check load and improve
conditions
Check, repair, or re-
place TEV
Adjust superheat
See item 3
Clean TEV and strainer
See item 12
Avoid compressor short
cycling or run compressor
enough to return oil to
crankcase, correct low load
conditions. Add oil.
Replace the compressor
Check superheat and TEV
operation
36
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