Temperature pull down to -30C

If I have to have a refrigeration machine that can bring down the temperature to -20C in a reefer container of size 40ft or 20ft, can I use the same refrigeration machine to obtain a temperature of
-30C (+/-3 C tolerance) in a test chamber of size 2m(L) x 2m (H) x 0.5m (w) which is much smaller size as compared to the reefer container when the cold air is recirculated to be more cold? If not, what will the maximum low temperature that this refrigeration machine can pull down in the test chamber? Kindly note, the refrigeration unit is placed in refrigeration chamber which is different from the test chamber. Cold air will be passed to the test chamber via ducts and recirculated back into the refrigeration chamber for further cooling. Please feel free to give any suggestions and ideas. Thanks

the reefer unit is too big to your chamber