To keep the box temperatures between -25F to -30F which you can't get with R134a without running at 18" Hg of vacuum or so while 404A would give about 5psig
This product I came across online looks exactly like a household chest freezer. The cabinet design, the coated aluminum interior and the location of drain and control.
It looks like they buy household freezers and mod them with off the shelf temperature controller and run it on 404A to get the temperature range they get.
Can you mod an HFC-134a to run cooler on HFC-404A with just a change to capillary tube or do you need? What exactly needs to be modded to make this work right?