The ultra-low temperature (-85) cooling method can be completed by applying the first or the first level compression freezer and the second phase of the second phase of the solid compression system to complete the two-way cooling cycle. Apply R-23 or R-13 on the second stage (primary) side and R410A R404 on the hard side (secondary). Be careful in selecting the secondary refrigeration oil (freezing oil) so as not to cause any disruption to continuous operation.