2201Q4JE-MY-C9-N_2018.01.
Chapter 6 Troubleshooting
Compound 2-stage Screw Compressor 4032**C
6-10
12: Compressor generates abnormal vibration and/or sound (continued)
Direct cause
Root cause
Action
Liquid flow-back during
operation
* Notable frosting on the
suction side.
* In many cases,
flow-back of mist
(steam) rather than
liquid occurs.
* Sometimes, gas-liquid
separator
(accumulator) is
attached to prevent
this symptom.
* See also the causes in
item 02, "Insufficient
refrigerant flow"
Aperture of liquid
supply expansion
valve is large
In case of temperature-type expansion valve,
check the condition of temperature sensitive
cylinder and capillary tube. If any defect is found,
take necessary actions.
If orifice gets unsuitable due to the change in
operating conditions, replace the orifice with
proper size one(s).
In case of electronic expansion valve, check
devices attached on the expansion valve aperture
control mechanism (circuit) such as temperature
sensor, converter, controller (overheating
regulator). If any of them is found defective,
replace it.
In the same way as with temperature-type
expansion valve, if orifice gets unsuitable due to
the change in operating conditions, replace the
orifice with proper size one(s).
Rapid change from
no-load operation to
full-load operation
Set control parameters so as to prevent rapid
changes.
Otherwise, make adjustment by throttling the
aperture of the capacity control increase-side oil
quantity adjusting valve.
Expansion valve
aperture control cannot
keep up with rapid
change in heat load on
the load side.
Avoid rapid change in heat load that exceeds the
set value of follow-up range of "heat exchanger on
load side (evaporator)" and "expansion valve".
For details, refer to the instruction manuals
related to devices/control on load side.
Heat exchange failure
in heat exchanger on
load side
・
Related to defrosting
In case of frosting (icing), conduct manual
defrosting.
Set defrosting interval shorter.
If a device which is specific to the defrosting type
fails, remove the cause(s) and replace the
device(s).
If a piping route which is specific to the defrosting
type gets blocked, remove the cause(s) and take
necessary actions.
* Especially when handling hot gas defrosting
systems, thoroughly read and understand the
contents of the instruction manuals for the units
associated with devices/control on the load side.
Heat exchange failure
in heat exchanger on
load side
・
Load side conditions
If ventilation around the heat exchanger is
obstructed for any reason such as piled up load,
improve the conditions.
* Ensure the flow of heating medium through the
heat exchanger on the load side.
Heat exchange failure
in heat exchanger on
load side
・
Heat exchanger
conditions
Check for any blocked heat transmission tubes or
fan motor(s) failure. If any problem is found, take
necessary actions.
