How fast does temperature in reefer decrease?

Depends on unit capacity as to how fast it gets cold

 

Also how good the insulation is, what kind of mechanical condition the reefer engine/chiller is in...

 

This too:

Heat always goes to cold and the larger the differential, the faster the transfer.....a physical property and a reefer removes heat. Doesn't add cold, but removes heat. So what Pony said and this is why.

 

Did you run out of fuel?

I'm not sure what you are asking with the reefer off? Are you asking product chill down times? or how long it will hold if you did run out of fuel or break down?

It depends if the box is frozen it might be 2 degrees an hour versus produce it won't keep very long as it needs air circulation. Most produce continues the ripening process or you might call it decomposing as it evaporates and gives off gases. Most customers have a 2 degree tolerance.

Being close to room temperature outside the sun will play a role on the box too.

Then one has to figure the core temperature of a pallet. It's like one big ice cube sitting there and the outside will probe different from the inside.