BLOCKSYSTEM FS Pag. 35 Rev. 02 02/07
UK
14. TROUBLESHOOTING TABLE
SYMPTOMS
CAUSES
Suction pressure too low
Suction pressure too high
Discharge pressure too low
Discharge pressure too high
Suction and discharge pressures tend to balance each other out
Suction tem
erature too low
Suction temperature too high
Discharge temperature too low
Discharge temperature too high
Excessive difference between inlet and outlet water temperature
Excessive difference between average water temperature and
condensing temperature
Compressor oil level too low
Hissing caused by the passage of gas through expansion parts
Thermostatic expansion valve blocked closed
Evaporator full or insufficiently defrosted
Gas bubbles can be seen through the indicator
Impossible to set the vacuum
Unusual noises inside the compressor
Frequent HP pressure switch cut out
Frequent LP pressure switch cut out
The compressor starts too quickly
The compressor works continuously
The compressor does not start up
Suction shut off valve closed or throttled
● ●
Discharge shut off valve closed or throttled
● ●
Suction valve or piston portions unsealed
● ● ● ● ●
Unsealed discharge valve
● ● ● ● ● ● ●
Clogged discharge pipes
● ●
Clogged suction pipes, wrongly sized suction pipes or
evaporator with insufficient power
●
Suction pipes not correctly insulated
●
Expansion valve capacity too high
● ● ● ● ●
Expansion valve capacity too low
● ● ● ● ● ●
Lifting of deposits caused by suction of liquid or foreign
matters
●
Clogged liquid pipes
● ●
By-pass shut off valve opened or perforated rupture disk
● ● ● ● ● ●
Gauge not set
● ● ● ● ●
Imprecise thermometer
● ● ● ● ● ●
Inadequate cooling water flow
● ● ● ●
Condenser dirty inside or outside
● ● ●
Evaporator to be defrosted; evaporator dirty inside or
outside. Presence of oil.
● ●
Presence of air or of gas that cannot be condensed
● ● ● ● ●
Condensing water temperature too high
● ●
Lack of refrigerant
● ● ● ● ● ● ● ● ● ●
Excess refrigerant
● ● ● ●
Clogged suction filter
● ● ●
Closed shut off valve on oil return pipe
●
Dirty filter on oil return
●
Connecting rod assembly, bearings or segments worn
●
Clogged expansion valve filter
● ● ● ● ●
Lack of oil
●
Ice formed on expansion valve needle
● ● ● ● ● ●
Expansion valve failure
● ● ● ● ● ● ● ● ● ● ● ●
Excess oil in the circuit
● ●
Condensing water too cool or too plentiful
●
Insufficient air flow to the air-cooled condenser
●
HP pressure switch incorrectly adjusted
●
Evaporator fan/s motor/s not working
●
LP pressure switch incorrectly adjusted
● ●
Excessive cooling requested
●
Refrigerating unit incorrectly set
●
Thermostat set too high or damaged
●
Current interrupted: fuse blown, thermomagnetic switch
contacts damaged
●
Closed solenoid valve on the liquid line
●
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