What are the miniature doors for on the trailer doors of reefers?

It's as semi retired said check temp and ventilation. Some loads if you have vent in front and back you can open both up and get air flow across product. Some produce put off gasses that hasten the ripening process and you need to get the gasses out when not running unit. You can on a nice cool night shut unit off open vents up on a load like watermelons save some fuel and still cool down load. Just one example many other loads are like that too. Trailer washout open them up and dry floor for free. Wouldn't have a reefer without at least one vent in front and back two would be better yet. The plus is you get steps on front vent and can actually get to radiator cap on older carrier units.

 

I duct taped one open once, with a little note. I was hauling onions, and almost every time I stopped, some driver who meant well would close it and let me know. I had to go through the company's terminal on the way east, and they removed everything. I read them the riot act for removing it, and then taped it open again.

 

They also come in handy if dropping a trailer after a washout it prevents the smell you get from water on aluminum floor .. We have a shipper we spot empties at that requires you to air it out after a wash or they refuse to load trailer if it has that stale smell from water ..

 

So customs can count how many aliens snuck in while your were eating lunch at the flying j in laredo.

 

If only they were counting there might not be 22 million of them in california.

 

what you did not want them blowing up?

 

It is a good idea too to keep a lock on it too as you would your trailer doors. Some cargo ie. Cherries/Blueberries can be easily taken through that smaller door if loaded by the pint.

 

its so the leprechauns can get out.

 

Agreed.