Hauling perishable loads is a bit of an art form, and requires strict attention to details, least an error or misunderstanding lead to a claim for a spoiled load. If the load is one product, then it’s fairly straight forward. Set the reefer to the required temperature, and off you go, making sure to check every 2 hours to verify the prescribed temperature is being maintained. As you may imagine, some perishables are far more temperature sensitive than others. The most sensitive being ice cream. It must be kept at -10°F at all times. Any variations can cause it to spoil. Others perishables are far less susceptible to temperature variations. Soft drinks and bottled water only need to be kept from freezing. Produce has some special handling requirements, mostly because it is shipped so that it ripens en route. Bananas are still days from ripening when shipped, and are shipped at 65°F, to help them ripen on the way. Broccoli is loaded on the trailer, then covered with about 2 cms of chipped ice, almost a slush, and the reefer is set to 36°F. The ice keeps the broccoli cold, and the 36°F slowly melts the ice, which keeps it fresh, then slowly drains out of the trailer.
Whatever perishable food products you’re hauling, be sure you read and understand the requirements fully. If you have any questions, ask your fleet manager. I’m sure they would rather field a bunch of questions than have a load end up in a dumpster because you didn’t understand something. Remember: the only “stupid question” is one you didn’t ask.