Thermal Alarm - IBM Medium J11 Hardware Installation And Maintenance Manual

Table 21. Thermal monitoring and control
Symptom
If the ambient air is below 25ºC
(77ºF), and the fans are observed
to increase in speed, then some
restriction on airflow may be
causing additional internal
temperature rise.
Note: This is not a fault
condition.

Thermal alarm

Table 22. Thermal alarm
Symptom
1. Front panel Module Fault LED
is amber.
2. Fan Fail LED is illuminated on
one or more PSUs.
Cause
The first stage in the thermal
control process is for the fans to
automatically increase in speed
when a thermal threshold is
reached. This may be caused by
higher ambient temperatures in
the local environment, and may
be perfectly normal.
Note: This threshold changes
according to the number of disks.
Cause
Internal temperature exceeds a
preset threshold for the
enclosure.
Chapter 6. Troubleshooting and problem solving 51
Recommended action
1. Check the installation for any
airflow restrictions at either
the front or back of the
enclosure. A minimum gap of
25 mm (1") at the front and
50 mm (2") at the rear is
recommended.
2. Check for restrictions due to
dust build-up. Clean as
appropriate.
3. Check for excessive re-
circulation of heated air from
rear to front. Use of the
enclosure in a fully enclosed
rack is not recommended.
4. Verify that all blank modules
are in place.
5. Reduce the ambient
temperature.
Recommended action
1. Verify that the local ambient
environment temperature is
within the acceptable range.
See also the Environmental
requirements section.
2. Check the installation for any
airflow restrictions at either
the front or back of the
enclosure. A minimum gap of
25 mm (1") at the front and
50 mm (2") at the rear is
recommended.
3. Check for restrictions due to
dust build-up. Clean as
appropriate.
4. Check for excessive re-
circulation of heated air from
rear to front. Use of the
enclosure in a fully enclosed
rack is not recommended.
5. If possible, shut down the
enclosure and investigate the
problem before continuing