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7
Troubleshooting
WARNING
Electrical connections! Electrical shock hazard! Before at tempt ing any
electrical troubleshooting, make sure all grounds are connected and s ecure
and there is ground continuity throughout the compressor system. Also
ensure the compressor system is correctly grounded to the power supply. If
you are not a qualified service person familiar with electrical troubleshooting
techniques, DO NOT PROCEED until a qualified service person is available.
Most in-warranty electrical failures are a result of mechanical problems (particles in t he oil, liquid
ref rigerant in the oil, etc.) and most mechanical problems are a result of system problems. Unless
the reason f or the f ailure is f ound, replacing the compressor will probably lead to another
compressor failure.
If the compressor f ails to start and run properly, it is important that the c ompressor b e t est ed to
determine its condition. It is possible that electrical components may be def ective, t he prot ector
may be open, or a saf ety device may be tripped. The most common compressor problems
encountered in the field are listed below.
Condition
The scroll
compressor does
not run, instead a
buzz sound can be
heard
32
Cause
Corrective action
Check the power supply on the compressor terminals if
Wired
there is voltage measured. Trace the wiring diagram to
incorrectly
see where the circuit is interrupted.
If the voltage falls below 90 % of the nameplate
Low supply
voltage, the motor may develop insufficient torque.
voltage
Make sure the compressor is supplied with rated
nominal voltage.
For a single-phase motor, a defective capacitor or relay
Def ective
may prevent the compressor from starting. Check these
components by substituting "a known-to-be-good"
capacitor or
relay
component if available. Make sure that the capacitors
are electrically discharged before checking.
Shorted or
Check the motor for ground by means of a continuity
grounded
check between the terminals. If grounded replace
motor windings
compressor.
▪
Ref rigerant migration: When the compressor is
switched off for a long period refrigerant can
condense in the crankcase. If the compressor body
is colder than the evaporator, refrigerant will move
f rom the evaporator to the compressor crankcase.
Ref rigerant migration normally occurs when the
compressor is installed in a cold area. A crankcase
heater and/or a pumpdown cycle provide good
protection against refrigerant migration.
Internal
▪
Acid formation: Acid forms in the presence of
compressor
moisture, oxygen, metal, salts, metal oxides and/or
mechanical
high discharge temperatures. The chemical
damage
reactions are accelerated at higher temperatures.
Oil and acid react with each other. Acid formation
leads to damage of the moving parts and in
extreme cases to motor burnout. Several different
test methods can be used to test for acid formation.
If acid is present a complete oil change (including
the oil in the oil separator) will help. A suction filter
which removes acid should also be fitted. Check
f ilter dryer condition.
AGL_HP_ST_ZHK1P_EN_Rev00
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