Air Conditioner
Fault Diagnosis
E-4
Prima PRO & Sentinel PRO Mass Spectrometers User Guide
Thermo Fisher Scientific
required.
Ambient
temperature
high
System designed for
temperatures up to 40˚C max.
Pressure switch
fault
Check status when powered off
& cool. If still in alarm, this
suggests a pressure switch fault.
a + c
Refrigerant
charge low
Check for leaks. Refill, as per
specification on air conditioner
label.
Pressure switch
fault
c
Internal fan
failure
Check internal fan – should be
running continuously. If not,
check supply and if fan can be
rotated freely.
Compressor
failure
Check compressor operation
(e.g. vibration, total current
drawn).
Discrepancy
(>3˚C
)between
Gasworks &
air con
temperature
readouts, not
controlling
Possible c
Fault in air con
sensor or
controller
Check mounting of sensors to
air con grille.
Check sensor connections.
Check response of sensors to
forced temperature changes e.g.
hand heat.
Use an independent temperature
measuring device to determine
which is correct.
Fault in
instrument
sensor or read-
back via ASU
Cabinet
temperature
not cycling
and reading
low
c
Cooling
continuously,
not regulating
Check operation of temperature
controller output contacts –
these may not be switching
correctly.
Check bypass valve – coil
resistance (not open circuit) and
supply (should be on when
temperature below set point)
Cycling time
>6 minutes
Possible c
(intermittent)
Bypass timeout
operating
Check if compressor is
switching off in each cycle.
Possible temperature controller
fault.
Liquid
(water) in
condensate
drain tube to
instrument
enclosure
None
Air con being
operated with
enclosure door
open
Switch off air conditioner when
door is open for any significant
time (depends on ambient
humidity).
Enclosure purge
air has too high
water content
Use instrument grade air with a
suitable known dew point.
