2025 Freezer Defrosting Season is upon us!

A Step-by-Step Guide to Defrosting Your Freezers

Laboratory freezer cleanouts are an essential part of laboratory maintenance. Freezers are often used to store temperature-sensitive samples, reagents, and other materials critical to scientific experiments. In the Freezer Challenge, we distinguish between “brushing the frost” out of a freezer and “doing a full defrost,” – which becomes necessary when frost builds up so much that it cannot easily be removed. This blog post focuses on a full defrost and the steps to take. Defrosting a freezer with too much ice buildup inside can help it run more efficiently and save energy!

1.  Plan ahead 

Before starting the clean-out process, have a plan in place. Determine which freezers need to be cleaned, who will be responsible for cleaning them, and what equipment and supplies will be required (absorbent towels, scraper, gloves, etc). 

2.  Empty the freezer
To clean the freezer properly, you'll need to empty it. Remove all samples, reagents, and other materials from the freezer and place them in a temporary storage area, usually another empty freezer. 

3. Defrost the freezer
If your freezer is frost-free, you can skip this step. However,  if your freezer accumulates frost, it's essential to defrost it before cleaning. Please turn off the freezer and let it defrost thoroughly. This may take several hours or days, so plan accordingly. You can allow your freezer to thaw out over the weekend with the door propped open, and it should have defrosted by Monday. Remember, puddles may accumulate on the floor – you may want to lay down absorbent material first and put signs so nobody slips in the water.

4.  Clean the freezer
Once the freezer is defrosted, it's time to clean it. Use a mild detergent and warm water to wipe down the freezer's interior. Pay special attention to areas where ice may have accumulated, such as around the door seal. Be sure to rinse the freezer thoroughly with water to remove any residue.

5.  Disinfect the freezer
After cleaning, the freezer must be disinfected to kill any remaining bacteria or viruses. Use a disinfectant spray or wipe to disinfect all freezer surfaces thoroughly. Follow the manufacturer's instructions for proper use.

6.  Dry the freezer
Use a clean towel to wipe down the freezer's interior, paying special attention to areas that may not be easy to reach.

7.  Return items to the freezer
Once the freezer is dry, turn it back on and allow it to return to its set point. Then, it's time to return all samples, reagents, and other materials to the freezer. Organize the items logically and label them appropriately. You may need to add items back to the freezer in batches to avoid keeping the door open too long.
 
8.  Document the cleanout
Finally, it's essential to document the clean-out process. Could you record who performed the cleanout, which freezer(s) were cleaned, and when the cleanout was performed? This documentation can be helpful for future reference and ensure the clean-out process is performed regularly.

9.  Record the action in your Freezer Challenge scoresheet and check out other suggestions on Good Management Practices here!