Thermo Scientific TSX Series Installation And Operation Manual page 45

Problem
Unit compressors run
continuously.
Cabinet temperature
reached an alarm 
condition, but suitable
alarm is not activated.
Problem with 
temperature 
validation/calibration.
Unit is experiencing too
much cabinet 
temperature fluctuation
(high uniformity / peak
variation).
Unit is constantly
alarming.
Unit cycle on-percentage
is increasing.
(Compressors are 
running more often than
before.)
40 | Troubleshooting Guide
Cause
Freezer set point is low.
Frost build up.
Dirty condenser.
Gasket damage.
Alarm setpoints may be
changed.
Cabinet temperature
displayed doesn't match
with actual temperature.
Operating mode selected.
Exterior door is closed but
not sealed completely.
Alarm icons appear on
user interface home
screen.
Door open alarm, exterior
door not closing
completely.
Door open alarm, exterior
door is closed but not
sealed completely.
Alarm set points may have
changed.
Ambient conditions.
Warm load (or) overload.
Frequent and prolonged
door openings.
Solution
Check whether the setpoint is in operating range. Change the
setpoint if necessary.
Defrost the unit. Refer Defrosting the Freezer
Clean the condenser and condenser filter.
Check for punctures or tears on gasket. Replace if necessary. 
Refer Gasket Maintenance.
Check the present setpoints for temperature alarm
conditions. Change the setpoints if required. Refer Alarms.
Customers performing on-site temperature calibration may
observe as much as a 2°C variation when an external probe
is placed next to the freezer control probe. This variation is
normal, due to optimization of control system to ensure
temperature uniformity throughout the cabinet.
Change power mode to high-performance mode to have
tighter peak variation. Refer Controls
Clean any ice build-up on gasket and / or cabinet surface.
Check for punctures or tears on gasket. Replace if necessary.
Refer Gasket Maintenance.
By pressing red bell or yellow triangle, the ticker message
provides alarm details and recovery details. Refer .
Open door completely and immediately close and latch it.
Defrost exterior door gasket and make sure the door is
completely sealed.
Change the set points as required. Refer Alarms.
Unit performance is directly impacted by these causes
mentioned. Try maintaining ambient conditions, reducing
load, reducing door openings.
Once temperature is stable, cycle dynamics should return to
normal range. If not call service.
.
.
Ultra Low Temperature Freezers