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Operation and maintenance instructions
Envistar / CRAMO
DSCR111125.01
Air handling with the focus on LCC
Continuous product development may give rise to specification changes without prior notice.
4
Fault Tracing
4.1 Fault Tracing Schedule for the Cooling Unit
Symptom
Possible cause
Remedial measure
Too high temperature in
cooled object/medium
The power supply is isolated.
No flow or bad flow across evaporator
The thermostat/control equipment is
set wrong/faulty.
The capacity controller is set for ex-
cessively high opening pressure.
The compressor is not operating.
Check the control/safety switch and
fuses.
Check that nothing stops the flow.
Adjust the setting or replace the
equipment.
Turn the opening screw anti-clockwise
1/6 of a turn at a time, read the tem-
perature change after 5 minutes, etc.
see illustration.
See "Compressor"
The unit is operating at re-
duced capacity and/or emits
high level of noise
The compressor is rotating in the
wrong direction
(
see illustration below
)
Transpose the order of the phase
wires.
Compressor is not operating The power supply is isolated.
The compressor safety circuit has
opened.
Malfunctioning compressor.
Check the control/safety switch and
fuses.
Check and reset, if needed.
Determine the fault. Replace compressor.
The compressor is switched
out by the low pressure
switch
Insufficient refrigerant.
No flow or bad flow across evaporator
Expansion valve is defective.
Faulty low pressure switch.
The system has a leak. Seal the leak
and charge more refrigerant.
Check the flow.
Check, replace.
Check, replace.
The compressor is switched
out by the high pressure
switch
No flow or bad flow across the con-
denser.
Faulty high pressure switch.
Check the flow across the condenser.
Check, replace.
Severe icing on the evapora-
tor
Expansion valve is incorrectly set/
defective.
Insufficient refrigerant.
Check, replace.
Check the sight glass. The system
has a leak. Seal the leak and charge
more refrigerant.
Pipes
Expansion valve
Capacity regulator
Determine that the cooling
unit is generating cooling in
the following way:
Check that there is a difference
in temperature between the
two uninsulated pipes that go
into the expansion valve. If this
is not the case: transpose the
two phase wires.
