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Diagnosis
Thermo Fisher Scientific
To determine if alarm c) is causing the general alarm, open the
enclosure door and quickly check the temperature reading on the air
conditioner controller (the temperature will start to change as soon as
the door is opened, so it is important to do this quickly). If the
temperature is more than ±2˚C from the set point, alarm c) will be
'on' (remember that other alarm conditions may also exist). The
default set point is 28˚C – press the 'P' button on the controller to
check the actual setting.
The only way to distinguish between alarms a) and b) is to check
within the unit using a DVM – refer to the manufacturers wiring
schematic. Since the unit will not run normally with any panels
removed or the door open, this is likely to require connecting test
leads and closing the door/panels to carry out measurements.
Table E–1
Fault
It gives the likely symptoms (including alarms) that could result from
failure of specific components within the system. It is unlikely to be
a comprehensive list
been encountered previously or considered (including the possibility
of multiple faults).
Once diagnosed, some faults can be straightforward to rectify, e.g.
replacement of electrical or electronic component. Anything
requiring repair or replacement of items within the refrigeration
circuit itself should only be attempted by a trained air conditioning
engineer, or by factory repair / replacement of the whole unit.
Table E–1. Air Conditioner Fault Diagnosis
Symptom
Cabinet
temperature
not cycling
and reading
high
gives a guide to diagnosing possible air conditioner faults.
–
there could be failure modes that have not
Alarm
Possible
cause
All
Air con mains
failure
a, b & c OK,
24VDC supply
but
fault
GasWorks
alarm shown
Alarm read-
back circuit
fault
b + c
External air
flow low
Prima PRO & Sentinel PRO Mass Spectrometers User Guide
Air Conditioner
Fault Diagnosis
Action/further
checks/comments
Check supply / breaker.
Check 24V reading via
Gasworks and DVM - PDU
3-pin connector pin 1 to pin 3
(see details above).
Link pin 2 to pin 3 to bypass air
con alarms to check if PDU is
functioning correctly.
Check air flow (by 'feel').
Set fan to full speed (safe area)
or increase air amplifier supply
pressure to maximum
(hazardous areas).
Inspect condenser fins, clean as
E-3
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