From my experience the effectiveness of the floor vents is quickly overwhelmed by the heat coming through the firewall
( or bulkhead for you Brits.) and are prone to leak in heavy rains.
Factory or aftermarket A/C is the way to go.........1978HJ45
It all depends on the climate you live in I reckon.
I've driven regularly in 40oC + temperatures in Oz where you tend to wind the windows up and close the vents to avoid the passing air from heating your skin. All my work vehicles there had NO airconditioning despite my working in the refrigeration/airconditioning business at that time. (Bloody Aussi cheapskate employers!
). I still remember the dark sweat-stains down my back (navy-blue work clothes) from the vinyl seats and remember the massive volumes of iced-water I had to drink to keep comfortable when working on those building-sites where I had no shelter from the sun. (But in such conditions I did enjoy the air conditioning in my BJ40 ... which was my private vehicle at the time.)
You learn fast if you're silly enough to wind down the window and rest your arm on the sill when the outside air is above body-temperature.
(Similarly you learn about the damage caused by picking up a spanner that's been left in the sun!)
But since moving back to New Zealand I've trashed the airconditioning. (I actually threw it away ... before I learnt that some people actually want to buy 2nd-hand air conditioning systems!)
There are occasions here in Summer when I can get uncomfortably hot ... but they don't occur often enough. And being hot and sweaty on those infrequent occasions makes the swims, beers, and icecreams all the more enjoyable.
Here .. the main benefit of airconditioning is the "demisting effect" it has on all internal surfaces in wet/humid inside conditions. But it still isn't worth carrying it around for the 95% of the year when it isn't required.
But ..... if I was back in Oz the airconditioning would have probably stayed put.
I've always actually hated airconditioning (despite working "in the trade"). So much so that even in Oz I turned it on only when temperatures got above 35 oC. Below that point - the kick vents and side-windows were my preferred option in the cruiser.
To look out at hot desert while being cocooned inside an airconditioned vehicle just seems altogether UNNATURAL and WRONG!
