Thermo Fisher Scientific ULT Freezers
Troubleshooting Guide | 19
Problem with temperature
validation/calibration.
Cabinet temperature
displayed doesn’t match
with actual temperature.
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 optimisation of the control
system to ensure temperature uniformity throughout the
cabinet.
Unit is constantly alarming.
Exterior door is closed but
not sealed completely.
Clean any ice build-up on gasket and/or cabinet surface.
Check for punctures or tears on gasket.
Door open alarm, exterior
door not closing
completely.
Open door completely and immediately close and latch it.
Door open alarm, exterior
door is closed but not
sealed completely.
Defrost exterior door gasket and make sure the door is
completely sealed.
Alarm set points may have
changed.
Change the set points as required.
Unit cycle on-percentage is
increasing (Compressors are
running more often than
before).
Ambient conditions.
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.
Warm load (or) over load.
Frequent and prolonged
door openings.
Difficult to close / open the
outer door.
Outer door alignment issues.
Unit is not level.
Make sure the unit is level.
in the user manual for levelling procedure.
Frost accumulated on
outer door gasket.
Scrape the ice occasionally on outer gasket.
Do not puncture gasket.
Door latch problem.
Ensure door latch is securing. If issue persists, call
service.
Difficult to close / open the
inner door.
Frost accumulated around
inner door.
Remove frost or ice build-up from inner door assembly.
Inner door latches
damaged.
Call service.
Vibration noise.
Rattling noise/ Loud noise.
Unit is not level.
Check if the unit is installed in a level area free from
vibration. (Refer
in user manual)
Loose side panels.
Check side panel screws, tighten them if necessary.
Rubber tubing separators
and/or compressor
dampeners may have
loosened.
Call service.
Problem
Cause
Solution
