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9
General Information
Thermistors
There are 3 thermistors used with the 3018/24 models.
• Zone Thermistor - Located on the right hand wall and is used to
maintain temperature.
• Evaporator Thermistor - Located on the back of the evaporator
plate and is used during defrost.
• Ambient Thermistor - Located in the base of the unit on the
condenser and is used to monitor ambient air temperatures.
Viewing Temperature
Note:
The display shows set point
NOT
the actual temperature.
The 3000 series is equipped with an advanced electronic display and
control. Thermistor readings can be obtained through both the
customer and service menu. The customer menu will display readings
while using offset calculations. It is important to note that the system
will use these adjusted readings when determining cooling and
defrost cycles. The service menu will display the actual thermistor
reading while disregarding offsets.
Customer Menu
To view the adjusted temperature of each available thermistor, follow
the steps below.
1. Initiate the customer menu by holding Select
for 5 seconds.
2. Use Down
to scroll to “Actual Temperatures”.
3. Press select
.
4. Use Up
or Down
to scroll through available information.
Service Menu
To view the actual temperature without having the offsets taken into
consideration, follow the steps below.
1. Initiate the service menu by holding both up
and Zone Toggle
for 5 seconds.
2. Use Up
or Down
to scroll to “Actual Temperatures”.
3. Press select
.
Use Up
or Down
to scroll through available information.
Thermistor Calibration
While thermistors generally do not require calibration, over time
contact corrosion and or element wear may make calibration
necessary.
Calibration
To calibrate a thermistor one must first prepare an ice water of
crushed ice and water in a suitable container. Allow the ice water
temperature to stabilize for at least 5 minutes before beginning.
NOTICE
Offsets are preset at the factory to efficiently maintain
product temperature. If modifying offset, existing values
must be taken into consideration.
NOTICE
Customer Care must be notified before any changes are
made to factory set offsets. Failure to notify Customer Care
will void the warranty.
1. Enter the service menu and record existing offset values for each
thermistor to be calibrated. See page
16
. Some models have a
factory offset setting of 0.
2. Change offset of each thermistor to be calibrated to 0.
3. Enter “Actual Temps” through the
Customer Menu
. See
“Viewing Temperature”.
4. Submerge the thermistor in the ice water. The temperature read
out through the menu should be 32°F. If different, record
difference.
5. Enter “Offsets” through the service menu and set the value
recorded in step 4 to the thermistor to be calibrated.
6. Enter “Actual Temps” through the
Customer Menu
, the
temperature readout should now be 32°F. If the readout is still
incorrect reset the offset to 0 and perform steps 4 & 5 again.
7. Enter the “Offsets” menu and add the value recorded in step 1 to
the new offset setting. For example, if after the ice water an offset
of 1 was needed and the existing offset value recorded in step 1
was -2 the new offset value would be -1. If the calculated value is
outside the maximum range capable in the offset menu the
thermistor must be replaced. The offset menu has a maximum
range of -10 through 10.
Note:
If a mistake is made in the calibration process a “Factory
Default” will restore offsets to their factory pre-set values. See
page
17
.
