70 | Troubleshooting
Controlled Rate Freezer
Troubleshooting
This section is a guide to troubleshooting general operational problems.
Table 14. Troubleshooting Table
Symptom
Possible Cause
Verification
Solution
Front UI LED
Not On
Power cord
unplugged
Verify power cord is plugged into outlet and
to unit power inlet
Plug in the power cord to the
outlet and to the unit power inlet
Breaker in 'Off'
Position
Verify the breaker position
Turn the breaker to the 'On'
position
Front UI LED
Red
Power cord
unplugged
Verify power cord is plugged into outlet and
to unit power inlet
Plug in the power cord to the
outlet and to the unit power inlet
Breaker in 'Off'
Position
Verify the breaker position
Turn the breaker to the 'On'
position
Heater Error
Alarm
LN
2
supply tank
empty
Verify supply tank contents adequate
Replace/Fill LN
2
Tank
Low LN
2
pressure
Verify tank pressure (regulator: 22# nominal)
Replace Tank/Regulator
LN
2
supply hose too
long
4’/6’ flex line to tank or vacuum insulated
plumbing
Replace/Upgrade Hose/
Plumbing
LN
2
solenoids bad
Check for valve counter warning dialogue
after run completion
Contact service to replace
valves
Erratic
Chamber
Temperature
High LN
2
Pressure
Verify tank pressure (regulator: 22# nominal)
Replace/Fill LN
2
Tank
Chamber
Thermocouple
Mounting
Verify that the chamber temperature probe
is properly seated in the sleeve by verifying
the blue marking is flush with the frame.
Refer to (calibration installation figure
number)
Adjust thermocouple position
Erratic
Sample
Temperature
Sample
thermocouple
positioning
If using a press, ensure sensor is oriented
properly to avoid metal contact
Correct the sensor orientation
so that it is not making contact
with the metal
Inaccurate
Chamber
Temperature
Old calibration
Verify last date of calibration is < 1 month
from the current date
Recalibrate probes
Inaccurate
calibration
Verify calibration values are reasonable.
Refer to calibration section for expected
range of values
Recalibrate probes
Inaccurate
Sample
Temperature
Old calibration
Verify last date of calibration is < 1 month
from the current date
Recalibrate probes
Inaccurate
calibration
Verify calibration values are reasonable.
Refer to calibration section for expected
range of values
Recalibrate probes