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Isotempâ Laboratory and Chromatography Refrigerators
Page 7 of 12
Part Number: 104416
Hold-Off Time
Error Codes
For Example:
The display indicates 4°C but a reference thermometer in the
refrigerator chamber indicates 6°C. The operator presses and holds
the Menu keypad for 5 seconds, then changes the display value from
0 to +2 by using the UP arrow key. Press the Menu key again. Now
the display indicates a chamber temperature of °6 C and the
controller begins to cool (as long as 3-min. delay period has expired)
to the desired temperature of 4°C as shown on the reference
thermometer.
Allow an additional 30 to 40 minutes for the refrigerator to again
stabilize. If the display is still inaccurate, repeat the calibration offset
procedure.
CAUTION: INCREASING the offset value DECREASES
the temperature at which the system controls. If the
offset is inadvertently set too high, the chamber’s
control temperature can fall below zero and cause
evaporator freeze-up. This is caused by the
evaporator temperature not rising above 0°C and not
defrosting during the compressor “off cycle”.
NOTE: While in any of the controller mode setups (temp set,
calibration offset or units), the controller will wait 15 seconds for
a new value to be entered. If there is no keypad operation within
the 15-second time window, control will automatically revert to
the temperature display mode and the Mode LED will turn off.
Following the offset menu is the hold-off (Ho) menu. The display will
momentarily flash “Ho”, followed by a number. The number shown is
the delay time in minutes between compressor activations. Use the
UP/DOWN keypads to change the value.
Increasing the hold-off time will allow additional time for the
evaporator to defrost during the off-cycle. This can reduce the
chance of evaporator freeze-up during times of high humidity.
Pressing the Menu keypad while in the Ho mode, enters the hold-off
time displayed, and returns controller operation to the temperature
display mode.
Error codes indicate when the controller is sensing a problem. A
description of each is given below. See the Troubleshooting Table
for additional information on error codes.
E1 Open sensor.
E2 Under temperature. Temperature at sensor is less than
–36°C.
E3 Over temperature. Temperature at sensor is greater than
37°C.