Terso Solutions, Inc.


Defrost Process, RFID Enclosure ULT (-80)

When preparing to defrost the freezer ensure that all product is removed and placed into an alternate safe ultra low storage location.

NOTE: When performing a defrost on a ULT with CO2 backup additional steps are needed, those additional CO2 specific steps will be noted later in this document

Power down the MOW (RFID Electronic box) located on the lower back of the ULT. Navigate to the main power switch on the bottom of the RFID box and flip it to the off position. You may hear an audible alarm when you disconnect the power. This is normal and will be silenced in the next step.

Proceed to the front of the unit; locate the lower control access panel at the bottom of the ULT, just below the main freezer door, and open the panel. We will now see various panel buttons and switches.  Locate the button with a sticker referencing power cycle (broken circle) as seen in the picture below. Press and hold the button for at a minimum of 3 seconds and release.  The audible beeping should cease at this point.

Proceed to the back of the ULT, navigate to the ON/OFF button on the bottom left and switch to the off position

Proceed to the front of the ULT and navigate to the lower control access panel at the bottom of the ULT. Locate the battery switch, as seen in the picture below, set to the off position and unplug the main power cable from the ULT

*CO2 - If the ULT at your location is supplied with a CO2 tank for backup purposes you will need to close the valve on the backup CO2 tank as seen in the picture below.  Close position will be turning the valve handle clockwise, do not over tighten.


  • Continue with the defrost procedure by opening all of the main inner metal door panels, also please place towels on the chamber floor. If the unit has a large amount of ice buildup we may need more towels.
  • Allow the frost to melt and become loose and remove the frost with a soft cloth

  • After defrosting is complete Plug the power for the ULT back in and turn the switch to the on position.

  • Then Proceed to the front of the unit behind the lower panel. Turn on the battery switch.

  • Then Proceed to the back of the unit to turn the power back on for the MOW(Electronic RFID unit on the back of the ULT)

  • Please allow the ULT to run empty overnight and fully return to temperature before reloading the product.

  • The Final step is to turn on the CO2 Tank

  • This completes the ULT defrost process