If you can't handle the heat, get out of the package car.
Crybabies want A/C and their employer to provide bottled water. Drivers these days are getting soft. Move on and let real men & women do the job.
I handle the heat everyday in blown out package cars and I have never had to come off road because of dehydration or heatstroke.. That being said, not everyone is built the same way and I have seen many of my experienced coworkers go home or to the hospital lately.
This isn't a "real men and women" thing, it's a common sense thing, and the fact is routes are heavier, cuts are more prolific and loaders are greener than I have ever seen.
The bottom line is the back needs ventilation, and UPS could pay for it all with the money they lose on Mondays alone.
As far as hydration goes I have froze Gatorade and water every summer night since I started working at UPS.
I don't trust a company that let's it's employees collapse on a regular basis to provide me anything