The title is incorrect of course as there is no such thing as an indentured trade as an air conditioning repairman. It is refrigeration mechanic or technician, which any but the uninformed, ignorant or obtuse would know.
There are many products that just would not be possible without refrigeration.
The first one which is currently one of the most important are the covid 19 vaccines, along with virtually all other vaccines in use. Many antibiotics also require refrigerated storage including amoxyllin, erythromycin and augmentin and for diabetics, life saving Insulin. Virtually all blood requires some form of refrigeration. Many medical diagnostic machines including MRI and CT machines are refrigerated to prevent overheating.
That fresh apple you just ate may have been upwards of six months old thanks to cold storage. Many fruits and vegetables are controlled ripened with refrigeration and certain gases including nitrogen carbon dioxide and ethylene. Allowing for consumption way past the actual season.
People can now eat fruits that cannot be grown in their own countries thanks to cold storage.
Snap frozen vegetables (thanks to an american Inventor in the 1880s named Clarence Birdseye who pioneered frozen food), can now be stored for long periods with little to no deterioration in nutritional content also keeping spoilage and therefore wastage to a minimum. in fact many fresh vegetables with limited shelf life have less nutritional value than frozen vegetables, unless consumed at peak freshness which is an extremely short period after picking.
The list of foods now available to us not only from far away places in our own countries but from overseas is almost endless from imported steak to seafood. (Carpet bag steak anyone?)
Imagine no fresh milk in ones' tea. Unthinkable!
Of course three of the less essential products should be enough for anyone to appreciate the humble "air conditioning repairman,"namely ice cream and beer, the latter being consumed in a nice air conditioned bar.
Here is a little snippet that you may find useful as a rule of thumb guide if you get this far in the thread:
Approximate time for bacteria* numbers to double in meat due to temperature change.
0°C (32F) 38 hours
4.5°C (40F) 12 hours
10°C (50F) 5 hours
21°C (70F) 1.5 hours
*dependent on type, product etc. Use at own risk. etc, etc.