Check that the evaporator is clear of any dust or debris, and that there is sufficient airflow around the machine. It may also help to reduce the temperature of the room. 

Check to make sure that the condenser fan is spinning. If you look through the holes on the right hand side of the machine you should be able to see the compressor fan. Go to settings, then manual hardware control, then turn on the refrigeration. The fan should turn on. If it does not a new fan motor is likely needed. 

For medium units with serial number below 1034, check to make sure the protector and or protector wire is not damaged or burn up. Watch this video [object Promise]

Check that there are no punctures or porosity in the refrigeration circuit inside the freeze dryer. If the test fails and the unit appears otherwise visibly undamaged, Contact Blue Alpine support.