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

Inspection door.

visual,
with a thermometer,
etc.......

 

When empty I tell my drivers to keep them open so trailer thieves and our good DOT buddies know.

 

It's a vent. Sometimes, product is loaded and it may be warm, but not require the reefer running, and it keeps air moving through the trailer.

 

The reefer trailers I use to pull had the cross-bar across the middle of the peep door, that is where I use to tie my mesh bag full of soft drinks to chill them down before sticking them in my cooler...and occasionally I would keep my pulp thermometer stuck thru a piece of duct tape hanging off of the cross-bar so I could get a quick check of the air temp at the back of the trailer.

 

It's to reach in and grab a handful of ice, in case of emergency, like when you hit yourself in the nards while raising/lowering your landing gear......

 

To hide your beer from DOT and keep it cold.

 

It's the exit for the Mexicans when they make it across the border. DUH!!!!

 

I got tired of other drivers telling me it was open so next time I stopped I took a permanent marker to the inside of the door and wrote "I know".

 

I thought that was where you hang the fake dead chicken at to let other chickens know you don't play around...I never haul fresh chickens so I don't have one. I have done plenty of frozen chickens tho. Take em to the port watch em come off your wagon go rite into the belly of a ship going to Russia. That was an experience.