Looking on the internet deeply has found these results:

coolbox is the most popular phrase on the web.

cool box 1526,000 results on the web	coolbox 11,530,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
I was so confident that I had put a bottle in he cool box. The sample should be conserved at a temperature of around 4º C, in a cool box or refrigerator until arrival at the laboratory. The sample should be conserved at a temperature of around 4ºC, in a cool box or refrigerator until arrival at the laboratory. First prepare the kebab meat, right out of the cool box since it cooks fast. The sample should be conserved at a temperature of around 4ºC, in a cool box or refrigerator (if possible) until arrival at the laboratory. It comes from the cool box in the back, it's tuned. The sample should be conserved at a temperature of around 4ºC, in a cool box or If transport of the extract is required, ensure delivery in a cool box within 24 to 48 hours.	It doesn't look like this phrase is very popular! The search could not find any examples on the internet.

cool box

1526,000 results on the web

coolbox

11,530,000 results on the web

More popular!

I was so confident that I had put a bottle in he cool box.
The sample should be conserved at a temperature of around 4º C, in a cool box or refrigerator until arrival at the laboratory.
The sample should be conserved at a temperature of around 4ºC, in a cool box or refrigerator until arrival at the laboratory.
First prepare the kebab meat, right out of the cool box since it cooks fast.
The sample should be conserved at a temperature of around 4ºC, in a cool box or refrigerator (if possible) until arrival at the laboratory.
It comes from the cool box in the back, it's tuned.
The sample should be conserved at a temperature of around 4ºC, in a cool box or
If transport of the extract is required, ensure delivery in a cool box within 24 to 48 hours.

It doesn't look like this phrase is very popular! The search could not find any examples on the internet.