i know nothing about trailer that makes things go brr

They have electric elements or gas back up for when room temperature starts to fall yes. But the response was to keeping the trailer warm which isn't really the normal thing, to do that they reverse the cycle of refrigeration so the indoor (trailer) coil is the warm one. Compressor still burning fuel.

 

Yup.

 

Also depends on temperature of the load before it is loaded.

Load product that is already frozen it isn't hard to keep it frozen. Load
"field temperature" produce on a 100 degree day and try to cool it
to 45 degrees............poor reefer will run non-stop trying to cool that down.

 

Am sure it’s something like that. Would be interesting to find out from the manufacturer.
On housing heat pumps. Many homeowners have found out the hard way. Through astronomical electric bills. It just don’t live up to the claims. That and I’m sure the builder didn’t get a heat pump with heating elements.

 

I've seen a few guys learn that the hard way. And scumbag receivers that look at you as free or cheap refrigerated warehouse space

 

Rule of thumb, when you fuel your truck, fuel the refer trailer.

 

Dennixx, Your doghouse pix reminds me of the picture of Flick
in "Christmas Story," with his tongue stuck to a flagpole.