Error Codes

Page 7 of 12	Isotemp Laboratory and Chromatography Refrigerators

Hold-Off Time

Part Number: 104416

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.