Advertisement
Condition
The Scroll
compressor does
not run, instead a
buzz sound can be
heard
The Scroll
compressor does
not run, no buzz
sound can be heard
AGL_HP_VS_YHV2P_E_Rev0
Cause
▪
Acid formation: Acid forms in the presence of
moisture, oxygen, metal, salts, metal oxides and/or
high discharge temperatures. The chemical
reactions are accelerated at higher temperatures.
Internal
Oil and acid react with each other. Acid formation
compressor
leads to damage of the moving parts and in
mechanical
extreme cases to motor burnout. Several different
damage
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
filter-drier condition.
Defective
Check if the pressure control or thermostat works
system control
properly or if the controls are open.
components
Power circuit
Check the fuse for a tripped circuit breaker or for an
open
open disconnected switch.
▪
If motor burned due to undersized contactors, you
will observe that the contacts welded together.
Complete motor burnout on all three phases
despite the presence of a functioning protection
Burned motor
system can be the result. For sizing information
winding
please consult with Contactor manufacturer data
sheet. If the application of the compressor is
changed the contactor sizing should be rechecked.
▪
Check for unbalanced voltage.
▪
For high discharge pressure:
-
-
-
High discharge
pressure /
suction
▪
For high suction pressure, check the "evaporator
pressure
superheat" first to diagnose the problem:
-
▪
Low superheat at the evaporator outlet is
characterized by oversized selection of the
expansion valve or incorrect bulb sensor mounting.
The valve may freeze up in the open position due to
accumulation of debris in the system. For a system
with very short refrigeration lines an accumulator is
recommended.
Corrective action
Check for system leaks.
Check the system design. Make sure the
discharge line is correctly sized: undersized
discharge line can increase discharge
pressure. This is also true for an undersized
condenser. Correct the component selection as
needed.
Check the fan motor, make sure it is running
properly in the right direction. Check the
condenser: if dirt has been accumulated it will
clog the airflow; clean as necessary. High
discharge pressure is also caused by an
overcharged system and high ambient
temperature surrounding the condenser.
High superheat at the evaporator outlet: this is
likely in case of excessive pressure-drop in the
liquid line or too much vertical lift on the pipe
work.
35
Advertisement
