temperature higher than set temp(-80c) at the bottom of freezer

Dear All,
I am newbie to refrigeration the cooling at the bottom of deep freezer is higher than set temperature (-80C ) diffrence between set and actual temperature is 10 to 15C. Freezer temp. sensor is at middle section of freezer Can anyone give me idea why such high temperature diffrence is ?
Thanks & Regards,
bhushan

That temperature difference exists because your freezer is not working as intended.


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Same problem for mostly for all deep freezer of different customer.

What is the size of the freezer? What refrigerant do you use?

hello ,is the compressors located below the freezer if so you will have heat from compressors etc effecting lower area of freezer ,,try loading up freezer with product will reduce temps but middle/display sensor will always read lower :)

Need more information, what brand of 'ultra low temp freezer' is it? What are you using it for and how often is the door open? Is there heavy ice build up inside the freezer? If so, relocate whatever is inside, defrost the freezer and restart. With heavy ice build up, oil logging is common with ULT freezers, this will cause poor performance