The CRYX cars instead of using Mechanical refeer units think teh ones on the Nose of a Trailer well they were cooled with IIRC Dry Ice or Liquid Nitorgen worked great for Frozen NOT SO GOOD WITH ANYTHING ELSE. See if your trying to get a backhaul and the only thing you can get is a frozen load of Potatoes and your in the Midwest YOUR SCREWED. Now with a Mechaincal reefer unit you can do whatever you need to reset the temp and go.