Leica Biosystems CM1100 - Manual (Page 24)

24 Instructions for use V1.3 RevB – 09/2012
8. Daily operation
8.7 Defrosting
The Leica CM 1100 provides both programmable auto-
matic and manual defrosting.
During a defrost cycle, whether automatic or manual,
the evaporator is flushed with hot gas to remove frost
that inevitably builds up during routine operation of a
cryostat. Such frost formation on the evaporator can
result in reduced cooling output.
Therefore, the automatic defrost cycle should be pro-
grammed to take place during the night hours to en-
sure that the operator has the required low tempera-
ture and thus good working conditions in the morning.
At installation sites with high air humidity increased
frost formation may occur, and it may become neces-
sary to start a manual defrost cycle in addition, which
can be operated any time when required.
The duration of the defrost cycles is set to 20
minutes in the factory.
The automatic defrost cycle is programmed
for 24.00 hrs in the factory.
A manual defrost cycle can be terminated
earlier.
After defrosting, cooling is resumed automatically. The
cryochamber will then be cooled to the previously se-
lected set temperature.
During defrosting, the actual chamber tem-
perature is displayed.
When activating a manual defrost cycle the
indication changes from LED 1 to LED 3. LED 3
illuminates for 10 minutes indicating the lead-
up of the defrost cycle.
When actual defrosting begins LED 2 illumi-
nates in addition.
At the end of the defrost cycle LED 2 and LED 3
extinguish, LED 1 is illuminated.
8.7.1 Programming an automatic defrost cycle
An automatic defrost cycle is programmed by enter-
ing the defrost time via the control unit (see 7.4.3).
8.7.2 Starting a manual defrost cycle
A manual defrost cycle is started and terminated via
the control unit (see 7.4.4 ).
Ambient temperatures above 35 °C may cause
defrosting problems.
In this case, a defrost cycle should not be op-
erated as this may cause severe damage to
the instrument.
When switching the instrument off overnight,
the lid should be removed from the cryo-
chamber to prevent condensation water in-
side.
When the instrument was switched off over-
night, a defrost cycle should be started before
resuming normal operation to prevent a loss
in refrigeration output.